Cladribine regimen for treating multiple sclerosis

ABSTRACT

The present invention relates to the use of multiple doses of Cladribine combined with beta interferon for the treatment of multiple sclerosis in patients who are refractory to at least one conventional therapy.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/301,083, filed Nov. 17, 2008, now U.S. Pat. No. 9,925,151, which is aU.S. national stage application of International Patent Application No.PCT/EP2007/055013, filed May 23, 2007, which claims the benefit of U.S.Provisional Patent Application No. 60/845,470, filed Sep. 18, 2006, thedisclosures of which are hereby incorporated by reference in theirentireties, including all FIGURES, tables and amino acid or nucleic acidsequences.

The Sequence Listing for this application is labeled “Seq-List.txt”which was created on Apr. 9, 2009 and is 1 KB. The entire content of thesequence listing is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to the use of multiple doses of Cladribinecombined with beta interferon for the treatment of multiple sclerosis inpatients who are refractory to at least one conventional therapy for MS.

BACKGROUND OF THE INVENTION

Multiple sclerosis (MS) is the most known chronic inflammatorydemyelinating disease of the central nervous system in humans. The onsetof the disease typically occurs during ages 20 to 40. Women are affectedapproximately twice as often as men.

Over time, MS may result in the accumulation of various neurologicaldisabilities. Clinical disability in MS is presumed to be a result ofrepeated inflammatory injury with subsequent loss of myelin and axons,leading to tissue atrophy.

MS is manifested in physical symptoms (relapses and disabilityprogression), Central Nervous System (CNS) inflammation, brain atrophyand cognitive impairment. Presenting symptoms include focal sensorydeficits, focal weakness, visual problems, imbalance and fatigue. Sexualimpairment and sphincter dysfunction may occur.

Approximately half of the patients with MS may experience cognitiveimpairment or depression.

MS is now considered to be a multi-phasic disease and periods ofclinical quiescence (remissions) occur between exacerbations. Remissionsvary in length and may last several years but are infrequentlypermanent.

Four courses of the disease are individualized: relapsing-remittingmultiple sclerosis (RRMS), secondary progressive multiple sclerosis(SPMS), primary progressive multiple sclerosis (PPMS) and progressiverelapsing multiple sclerosis (PRMS).

More than 80% of patients with MS will initially display a RRMS coursewith clinical exacerbation of neurological symptoms, followed by arecovery that may or may not be complete (Lublin and Reingold,Neurology, 1996, 46:907-911).

During RRMS, accumulation of disability results from incomplete recoveryfrom relapses. Approximately, half of the patients with RRMS switch to aprogressive course, called SPMS, 10 years after the diseased onset.During the SP phase, worsening of disability results from theaccumulation of residual symptoms after exacerbation but also frominsidious progression between exacerbations (Lublin and Reingold above).10% of MS patients have PPMS which is characterized by insidiousprogression of the symptoms from the disease onset. Less than 5% ofpatients have PRMS and are often considered to have the same prognosisas PPMS. It is suggested that distinct pathogenic mechanisms may beinvolved in different patient sub-groups and have wide-rangingimplications for disease classification (Lassmann et al., 2001, TrendsMol. Med., 7, 115-121; Lucchinetti et al., Curr. Opin. Neurol., 2001,14, 259-269).

MS onset is defined by the occurrence of the first neurological symptomsof CNS dysfunction. Advances in cerebrospinal fluid (CSF) analysis andmagnetic resonance imaging (MRI) have simplified the diagnostic processand facilitated early diagnostic (Noseworthy et al., The New EnglandJournal of Medicine, 2000, 343, 13, 938-952). The International Panel onthe Diagnosis of MS issued revised criteria facilitating the diagnosisof MS and including MRI together with clinical and para-clinicaldiagnostic methods (Mc Donald et al., 2001, Ann. Neurol., 50:121-127).

Current medications for MS which are disease modifying treatments, i.e.modifying the course of MS, modulate or suppress the immune system.There are four FDA approved immunomodulating agents for RRMS: three betainterferons (Betaseron®, Berlex; Avonex®, Biogen; Rebif®, Serono) andGlatimarer Acetate (Copaxone®, Teva). There is also one FDA approvedimmunosuppressing drug for worsening MS, Mitoxantrone (Novantrone®,Serono). Several other immunosuppressive agents are used, although notFDA approved.

Among them, Cladribine, a chlorinated purine analogue2-chloro-2′deoxyadenosine (2-CdA), has been suggested to be useful inthe treatment of MS (EP 626853B1 and U.S. Pat. No. 5,506,214).

Several clinical studies with Cladribine in patients with multiplesclerosis have investigated the use of i.v. and s.c. Cladribine in MS.

Two double-blind, placebo controlled Phase II studies were conductedrespectively in the treatment of Chronic Progressive MS (Selby et al.,1998, Can. J. Neurol. Sci., 25:295-299) and Relapsing-Remitting MSrespectively (Romine et al., 1999, Proceedings of the Association ofAmerican Physicians, 111, 1, 35-44).

In the first trial, the Cladribine dose used was 0.1 mg/kg/day for 7days by continuous i.v. infusion. The treatment for repeated for 4consecutive months.

In the second clinical trial, the Cladribine dose used was 0.07mg/kg/day for 5 days by subcutaneous injection. The treatment wasrepeated for 6 consecutive months.

In addition, placebo controlled Phase III study was conducted inpatients with primary progressive (PP) or secondary progressive (SP)multiple sclerosis (Rice at al., 2000, Neurology, 54, 5, 1145-1155). Inthis study, both patient groups received Cladribine by subcutaneousinjection at a dose of 0.07 mg/kg/day. The treatment was repeated foreither 2 months or 6 months.

The Phase II clinical studies provided evidence for the positive effectsof Cladribine in patients with MS in terms of Kutzke Extended DisabilityStatus Scale (EDSS), Scripps Neurologic rating Scale (SNRS) scores andMagnetic Resonance Imaging (MRI) findings (Beutler et al., 1996, Proc.Nat. Acad. Sci. USA, 93, 1716-1720; Romine et al., 1999 above). PhaseIII study results, were positive on the significant reduction ofMRI-measured brain lesions (Rice at al., 2000, above).

Some adverse effects (AEs), such as increased incidence of infectionsrelated to compromised immune function or myelosuppression, wereobserved with the highest doses (Selby et al., 1998, above; Beutler etal., 1994, Acta hematol., 91:10-15). Due to the narrow margin of safetybetween the efficacy dose and the dose of occurrence of AEs, to date,all clinical trials for Cladribine in multiple sclerosis have beenconducted using either i.v. or s.c. administration. As a result, Beutleret al. (Beutler et al., 1996, Seminars in Hematology, 33, 1(S1), 45-52)excluded the oral route for the treatment of multiple sclerosis withCladribine.

Grieb et al. reported a small trial in 11 patients withremitting-relapsing multiple sclerosis (Grieb et al., 1995, ArchivumImmunologiae et Therapiae Experimentalis, 43 (5-6), 323-327) whereinCladribine has been orally administered during 6 monthly courses of 5days at a total dose of about 4-5.7 mg/kg (patients of about 52 andabout 75 kilos, respectively) i.e. a total effective dose of 2-2.85mg/kg. For some patients, a single re-treatment of 5 days was performedat a cumulative dose of 0.4-0.66 mg/kg after a cladribine free-period of3 or 6 months. The side effects observed with the regimen above weresaid to be less severe than the ones observed in the study on patientssuffering from chronic progressive multiple sclerosis treated by i.v.infusion of Cladribine (Sipe et al., 1994, Lancet, 344, 9-13) but werestill present. In addition, the therapeutic efficacy of the oral regimenabove versus the i.v. infusion therapy was questioned (Grieb et al.,1995, above) and a group of “non-responders” has been identified(Stelmasiak et al., 1998, Laboratory Investigations, 4(1), 4-8).

Therefore, it would be desirable to have a method for treating multiplesclerosis comprising the oral administration of Cladribine that wouldpermit the same or improved effect on MS lesions while decreasing theoccurrence and/or severity adverse events. In addition, as MS is achronic disease, it would be desirable to decrease the occurrence and/orseverity adverse events in such a way that re-treatments are possible. Asustained benefit of Cladribine treatment between the treatment periodsis also desirable.

It would also be desirable to have a method for treating multiplesclerosis that would permit the treatment of patients who are refractoryto at least one conventional therapy.

SUMMARY OF THE INVENTION

The present invention is directed towards the use of Cladribine combinedwith beta interferon for the preparation of a pharmaceutical formulationfor the treatment of multiple sclerosis, wherein the Cladribinepreparation is to be the orally administered.

Particularly, the invention is directed towards the use of Cladribinecombined with beta interferon for the preparation of a medicament forthe treatment of patients who are refractory to at least oneconventional therapy.

An embodiment of the invention provides an improved dosing regimen forCladribine combined with beta interferon in the treatment of multiplesclerosis.

An additional embodiment of the invention provides the use of Cladribinecombined with beta interferon for the preparation of a pharmaceuticalformulation for the treatment of multiple sclerosis wherein adverseeffects are reduced, allowing further use of Cladribine.

In one embodiment, the invention provides:

1. The use of a combination of Cladribine and IFN-beta for themanufacture of a medicament for treating patients suffering frommultiple sclerosis and who are refractory to at least one conventionaltherapy for multiple sclerosis, wherein Cladribine is to be orallyadministered following the sequential steps below:

(i) An induction period wherein Cladribine is administered and whereinthe total dose of Cladribine reached at the end of the induction periodis from about 1.7 mg/kg to about 3.5 mg/kg;

(ii) A Cladribine-free period wherein no Cladribine is administered;

(iii) A maintenance period wherein Cladribine is administered andwherein the total dose of Cladribine administered during the maintenanceperiod is lower than or equal to the total dose of Cladribine reached atthe end of the induction period (i);

(iv) A Cladribine-free period wherein no Cladribine is administered.

In another embodiment, the invention provides:

2. The use of a combination of Cladribine and IFN-beta for treatingpatients suffering from multiple sclerosis and who are refractory to atleast one conventional therapy for multiple sclerosis, comprising theoral administration of Cladribine following the sequential steps below:

(i) An induction period wherein Cladribine is administered and whereinthe total dose of Cladribine reached at the end of the induction periodis from about 1.5 mg/kg to about 3.5 mg/kg;

(ii) A Cladribine-free period wherein no Cladribine is administered;

(iii) A maintenance period wherein Cladribine is administered andwherein the total dose of Cladribine administered during the maintenanceperiod is lower than or equal to the total dose of Cladribine reached atthe end of the induction period (i);

(iv) A Cladribine-free period wherein no Cladribine is administered.

In another embodiment, the invention provides:

3. A product comprising Cladribine and IFN-beta as a combinedpreparation for simultaneous, separate or sequential use in the therapyof patients suffering from multiple sclerosis and who are refractory toat least one conventional therapy for multiple sclerosis, whereinCladribine is to be orally administered following the sequential stepsbelow:

(i) An induction period wherein Cladribine is administered and whereinthe total dose of Cladribine reached at the end of the induction periodis from about 1.7 mg/kg to about 3.5 mg/kg;

(ii) A Cladribine-free period wherein no Cladribine is administered;

(iii) A maintenance period wherein Cladribine is administered andwherein the total dose of Cladribine administered during the maintenanceperiod is lower than or equal to the total dose of Cladribine reached atthe end of the induction period (i);

(iv) A Cladribine-free period wherein no Cladribine is administered.

In another embodiment, the invention provides:

4. The use or product according to point 1, 2 or 3 here above, whereinthe induction period lasts up to 4 months, or up to 3 months, or up to 2months.

In another embodiment, the invention provides:

5. The use or product according to any one of points 1 to 4 here abovewherein the induction period lasts up to 2 months and the total dose ofCladribine reached at the end of the induction period is about 1.7mg/kg, preferably 1.75 mg/kg.

In another embodiment, the invention provides:

6. The use or product according to any one of points 1 to 4 here abovewherein the induction period lasts up to 4 months and the total dose ofCladribine reached at the end of the induction period is about 3.5mg/kg, preferably 3.5 mg/kg.

In another embodiment, the invention provides:

7. The use or product according to any of points 1 to 5 here abovewherein the Cladribine-free period (ii) lasts up to 10 months, or up to9 months, or up to 8 months.

In another embodiment, the invention provides:

8. The use or product according to point 7 here above wherein theCladribine-free period (ii) lasts 8 months.

In another embodiment, the invention provides:

9. The use or product according to any one of points 1 to 8 here abovewherein the Cladribine-free (iv) period lasts up to 10 months.

In another embodiment, the invention provides:

10. The use or product according to any one of points 1 to 9 here abovewherein the combined duration of the induction period (i) with theCladribine-free period (ii) is about 1 year (about 12 months).

In another embodiment, the invention provides:

11. The use or product according to point 10 here above wherein theduration of the induction period is about 4 months and the duration ofthe Cladribine-free period (ii) is about 8 months, or the duration ofthe induction period is about 3 months and the duration of theCladribine-free period (ii) is about 9 months, or the duration of theinduction period is about 2 months and the duration of theCladribine-free period (ii) is about 10 months.

In another embodiment, the invention provides:

12. The use or product according to any one of points 1 to 9 here abovewherein the combined duration of the induction period (i) with theCladribine-free period (ii) is about 1 year (about 12 months) and thetotal dose of Cladribine reached at the end of this year of treatment isabout 1.7 mg/kg, preferably 1.75 mg/kg or about 3.5 mg/kg, preferably3.5 mg/kg.

In another embodiment, the invention provides:

13. The use or product according to point 12 here above wherein theduration of the induction period is about 4 months and the duration ofthe Cladribine-free period (ii) is about 8 months, or the duration ofthe induction period is about 3 months and the duration of theCladribine-free period (ii) is about 9 months, or the duration of theinduction period is about 2 months and the duration of theCladribine-free period (ii) is about 10 months.

In another embodiment, the invention provides:

14. The use or product according to any one of points 1 to 13 here abovewherein the maintenance period lasts up to 4 months, or up to 3 monthsor up to 2 months.

In another embodiment, the invention provides:

15. The use or product according to any one of points 1 to 14 here abovewherein the maintenance period lasts up to 2 months and the total doseof Cladribine administered during the maintenance period is about 1.7mg/kg, preferably 1.75 mg/kg.

In another embodiment, the invention provides:

16. The use or product according to any one of points 1 to 15 here abovewherein the combined duration of the maintenance period (iii) with theCladribine-free period (iv) is about 1 year (about 12 months).

In another embodiment, the invention provides:

17. The use or product according to point 16 here above wherein theduration of the maintenance period (iii) is about 4 months and theduration of the Cladribine-free period (iv) is about 8 months, or theduration of the maintenance period (iii) is about 3 months and theduration of the Cladribine-free period (iv) is about 9 months.

In another embodiment, the invention provides:

18. The use or product according to point 16 here above wherein theduration of the maintenance period (iii) is about 2 months and theduration of the Cladribine-free period (iv) is about 10 months.

In another embodiment, the invention provides:

19. The use or product according to point 16 here above wherein thecombined duration of the maintenance period (iii) with theCladribine-free period (iv) is about 1 year (about 12 months) and thetotal dose of Cladribine administered during this year of treatment isabout 1.7 mg/kg, preferably 1.75 mg/kg.

In another embodiment, the invention provides:

20. The use or product according to point 19 here above wherein theduration of the maintenance period (iii) is about 4 months and theduration of the Cladribine-free period (iv) is about 8 months, or theduration of the maintenance period (iii) is about 3 months and theduration of the Cladribine-free period (iv) is about 9 months.

In another embodiment, the invention provides:

21. The use or product according to point 19 here above wherein theduration of the maintenance period (iii) is about 2 months and theduration of the Cladribine-free period (iv) is about 10 months.

In another embodiment, the invention provides:

22. The use or product according to any one of points 1 to 21 here abovewherein the combined duration of the induction period (i), theCladribine-free period (ii), the maintenance period (iii) and theCladribine-free period (iv) is about 2 years (about 24 months).

In another embodiment, the invention provides:

23. The use or product according to point 22 here above wherein:

-   -   the duration of the induction period is about 4 months, the        duration of the Cladribine-free period (ii) is about 8 months,        the duration of the maintenance period (iii) is about 4 months        and the duration of the Cladribine-free period (iv) is about 8        months or;    -   the duration of the induction period is about 4 months, the        duration of the Cladribine-free period (ii) is about 8 months,        the duration of the maintenance period (iii) is about 3 months        and the duration of the Cladribine-free period (iv) is about 9        months, or;    -   the duration of the induction period is about 4 months, the        duration of the Cladribine-free period (ii) is about 8 months,        the duration of the maintenance period (iii) is about 2 months        and the duration of the Cladribine-free period (iv) is about 10        months, or;    -   the duration of the induction period is about 3 months, the        duration of the Cladribine-free period (ii) is about 9 months,        the duration of the maintenance period (iii) is about 4 months        and the duration of the Cladribine-free period (iv) is about 8        months, or;    -   the duration of the induction period is about 3 months, the        duration of the Cladribine-free period (ii) is about 9 months,        the duration of the maintenance period (iii) is about 3 months        and the duration of the Cladribine-free period (iv) is about 9        months, or;    -   the duration of the induction period is about 3 months, the        duration of the Cladribine-free period (ii) is about 9 months,        the duration of the maintenance period (iii) is about 2 months        and the duration of the Cladribine-free period (iv) is about 10        months, or;    -   the duration of the induction period is about 2 months, the        duration of the Cladribine-free period (ii) is about 10 months,        the duration of the maintenance period (iii) is about 4 months        and the duration of the Cladribine-free period (iv) is about 8        months, or;    -   the duration of the induction period is about 2 months, the        duration of the Cladribine-free period (ii) is about 10 months,        the duration of the maintenance period (iii) is about 3 months        and the duration of the Cladribine-free period (iv) is about 9        months, or;    -   the duration of the induction period is about 2 months, the        duration of the Cladribine-free period (ii) is about 10 months,        the duration of the maintenance period (iii) is about 2 months        and the duration of the Cladribine-free period (iv) is about 10        months.

In another embodiment, the invention provides:

24. The use or product according to point 22 here above wherein thecombined duration of the induction period (i) and the Cladribine-freeperiod (ii) is about 1 year (12 months), the combined duration of themaintenance period (iii) and the Cladribine-free period (iv) is about 1year (about 12 months), the total dose of Cladribine administered duringthe first year of treatment is about 1.7 mg/kg, preferably 1.75 mg/kgand the total dose of Cladribine administered during the second year oftreatment is about 1.7 mg/kg, preferably 1.75 mg/kg.

In another embodiment, the invention provides:

25. The use or product according to point 24 here above wherein:

-   -   the duration of the induction period is about 4 months, the        duration of the Cladribine-free period (ii) is about 8 months,        the duration of the maintenance period (iii) is about 4 months        and the duration of the Cladribine-free period (iv) is about 8        months or;    -   the duration of the induction period is about 4 months, the        duration of the Cladribine-free period (ii) is about 8 months,        the duration of the maintenance period (iii) is about 3 months        and the duration of the Cladribine-free period (iv) is about 9        months, or;    -   the duration of the induction period is about 4 months, the        duration of the Cladribine-free period (ii) is about 8 months,        the duration of the maintenance period (iii) is about 2 months        and the duration of the Cladribine-free period (iv) is about 10        months, or;    -   the duration of the induction period is about 3 months, the        duration of the Cladribine-free period (ii) is about 9 months,        the duration of the maintenance period (iii) is about 4 months        and the duration of the Cladribine-free period (iv) is about 8        months, or;    -   the duration of the induction period is about 3 months, the        duration of the Cladribine-free period (ii) is about 9 months,        the duration of the maintenance period (iii) is about 3 months        and the duration of the Cladribine-free period (iv) is about 9        months, or;    -   the duration of the induction period is about 3 months, the        duration of the Cladribine-free period (ii) is about 9 months,        the duration of the maintenance period (iii) is about 2 months        and the duration of the Cladribine-free period (iv) is about 10        months, or;    -   the duration of the induction period is about 2 months, the        duration of the Cladribine-free period (ii) is about 10 months,        the duration of the maintenance period (iii) is about 4 months        and the duration of the Cladribine-free period (iv) is about 8        months, or;    -   the duration of the induction period is about 2 months, the        duration of the Cladribine-free period (ii) is about 10 months,        the duration of the maintenance period (iii) is about 3 months        and the duration of the Cladribine-free period (iv) is about 9        months, or;    -   the duration of the induction period is about 2 months, the        duration of the Cladribine-free period (ii) is about 10 months,        the duration of the maintenance period (iii) is about 2 months        and the duration of the Cladribine-free period (iv) is about 10        months.

In another embodiment, the invention provides:

26. The use or product according to point 22 here above wherein thecombined duration of the induction period (i) and the Cladribine-freeperiod (ii) is about 1 year (12 months), the combined duration of themaintenance period (iii) and the Cladribine-free period (iv) is about 1year (about 12 months), the total dose of Cladribine administered duringthe first year of treatment is about 3.5 mg/kg, preferably 3.5 mg/kg andthe total dose of Cladribine administered during the second year oftreatment is about 1.7 mg/kg, preferably 1.75 mg/kg.

In another embodiment, the invention provides:

27. The use or product according to point 26 here above wherein:

-   -   the duration of the induction period is about 4 months, the        duration of the Cladribine-free period (ii) is about 8 months,        the duration of the maintenance period (iii) is about 4 months        and the duration of the Cladribine-free period (iv) is about 8        months or;    -   the duration of the induction period is about 4 months, the        duration of the Cladribine-free period (ii) is about 8 months,        the duration of the maintenance period (iii) is about 3 months        and the duration of the Cladribine-free period (iv) is about 9        months, or;    -   the duration of the induction period is about 4 months, the        duration of the Cladribine-free period (ii) is about 8 months,        the duration of the maintenance period (iii) is about 2 months        and the duration of the Cladribine-free period (iv) is about 10        months, or;    -   the duration of the induction period is about 3 months, the        duration of the Cladribine-free period (ii) is about 9 months,        the duration of the maintenance period (iii) is about 4 months        and the duration of the Cladribine-free period (iv) is about 8        months, or;    -   the duration of the induction period is about 3 months, the        duration of the Cladribine-free period (ii) is about 9 months,        the duration of the maintenance period (iii) is about 3 months        and the duration of the Cladribine-free period (iv) is about 9        months, or;    -   the duration of the induction period is about 3 months, the        duration of the Cladribine-free period (ii) is about 9 months,        the duration of the maintenance period (iii) is about 2 months        and the duration of the Cladribine-free period (iv) is about 10        months, or;    -   the duration of the induction period is about 2 months, the        duration of the Cladribine-free period (ii) is about 10 months,        the duration of the maintenance period (iii) is about 4 months        and the duration of the Cladribine-free period (iv) is about 8        months, or;    -   the duration of the induction period is about 2 months, the        duration of the Cladribine-free period (ii) is about 10 months,        the duration of the maintenance period (iii) is about 3 months        and the duration of the Cladribine-free period (iv) is about 9        months, or;    -   the duration of the induction period is about 2 months, the        duration of the Cladribine-free period (ii) is about 10 months,        the duration of the maintenance period (iii) is about 2 months        and the duration of the Cladribine-free period (iv) is about 10        months.

In another embodiment, the invention provides:

28. The use or product according to any one of points 1 to 27 here abovewherein steps (iii) to (iv) are repeated one, two or three times.

In another embodiment, the invention provides:

29. The use or product according to any one of points 1 to 28 here abovewherein the induction period lasts during 2 months, the total dose ofCladribine reached at the end of the induction period is 1.75 mg/kg, theCladribine-free period (ii) lasts during 10 months, the maintenanceperiod lasts during 2 months and the total dose of Cladribineadministered during the maintenance period is 1.75 mg/kg.

In another embodiment, the invention provides:

30. The use or product according to point 29 here above wherein theCladribine-free (iv) period lasts during 10 months.

In another embodiment, the invention provides:

31. The use or product to any one of points 1 to 28 here above whereinthe induction period lasts during 4 months, the total dose of Cladribinereached at the end of the induction period is 3.5 mg/kg, theCladribine-free period (ii) lasts during 8 months, the maintenanceperiod lasts during 2 months and the total dose of Cladribineadministered during the maintenance period is 1.75 mg/kg, theCladribine-free (iv) period lasts during 10 months.

In another embodiment, the invention provides:

32. The use or product according to point 31 here above wherein theCladribine-free (iv) period lasts during 10 months.

In another embodiment, the invention provides:

33. The use or product according to any one of points 1 to 32 here abovewherein steps (iii) to (iv) are repeated one time.

In another embodiment, the invention provides:

34. The use or product according to any one of points 1 to 33 here abovewherein the bioavailability of Cladribine is of about 40%.

In another embodiment, the invention provides:

35. The use or product according to any one of points 1 to 34 here abovewherein the total effective dose of Cladribine reached at the end of theinduction period is from about 0.7 mg/kg to about 1.4 mg/kg.

In another embodiment, the invention provides:

36. The use or product according to any one of points 1 to 35 here abovewherein the total effective dose of Cladribine reached at the end of theinduction period is about 0.7 mg/kg or about 1.4 mg/kg.

In another embodiment, the invention provides:

36. The use or product according to any one of points 1 to 36 here abovewherein the total effective dose of Cladribine administered during themaintenance period is about 0.7 mg/kg.

In another embodiment, the invention provides:

37. The use or product according to any one of points 1 to 36 here abovewherein Cladribine is administered from 4 to 7 days per month,preferably 4 or 5 days per month, during the induction period.

In another embodiment, the invention provides:

38. The use or product according to point 37 here above whereinCladribine is administered from day 1 to day 5, or from day 1 to day 4,each month during the induction period.

In another embodiment, the invention provides:

39. The use or product according to point 37 or 38 here above whereinCladribine is administered at a daily dose of about 0.175 mg/kg duringthe induction period.

In another embodiment, the invention provides:

40. The use or product according to point 37, 38 or 39 here abovewherein Cladribine is administered several times a day during theinduction period, preferably twice or three times a day, more preferablytwice a day.

In another embodiment, the invention provides:

41. The use or product according to any one of points 1 to 40 here abovewherein Cladribine is administered from 4 to 7 days per month,preferably 4 or 5 days per month, during the maintenance period.

In another embodiment, the invention provides:

42. The use or product according to point 41 here above whereinCladribine is administered from day 1 to day 5, or from day 1 to day 4each month during the maintenance period.

In another embodiment, the invention provides:

43. The use or product according to points 41 or 42 here above whereinCladribine is administered at a daily dose of about 0.175 mg/kg duringthe maintenance period.

In another embodiment, the invention provides:

44. The use or product according to point 41, 42 or 43 here abovewherein Cladribine is administered several times a day during themaintenance period, preferably twice or three times a day, morepreferably twice a day.

In another embodiment, the invention provides:

45. The use or product according to any one of points 1 to 44 here abovewherein IFN-beta is administered simultaneously, separately orsequentially with oral Cladribine.

In another embodiment, the invention provides:

46. The use or product according to point 45 here above wherein IFN-betais administered before the induction period (i), and/or after themaintenance period (iii).

In another embodiment, the invention provides:

47. The use or product according to point 45 here above wherein IFN-betais administered during the Cladribine-free period (ii) and/or (iv).

In another embodiment, the invention provides:

48. The use or product according to point 45 here above wherein IFN-betais administered simultaneously with oral Cladribine.

In another embodiment, the invention provides:

49. The use or product according to point 48 here above wherein IFN-betais administered during the induction period (i) and/or the maintenanceperiod (iv).

In another embodiment, the invention provides:

50. The use or product according to point 49 here above wherein IFN-betais administered during the induction period (i), the maintenance period(iv) and the Cladribine-free periods (ii) and (iv).

In another embodiment, the invention provides:

51. The use or product according to point 50 here above wherein IFN-betais administered before the induction period (i), during the inductionperiod (i), during the maintenance period (iv), during theCladribine-free periods (ii) and (iv) and after the Cladribine-freeperiod (iv).

In another embodiment, the invention provides:

52. The use or product according to any one of points 1 to 51 whereinthe IFN-beta is chosen in the group consisting of: interferon-beta 1aand interferon-beta 1b.

In another embodiment, the invention provides:

53. The use or product according to point 52 here above wherein theIFN-beta is chosen in the group consisting of: Avonex® (Biogen), Rebif®(Serono), and Betaseron® (Berlex/Schering AG).

In another embodiment, the invention provides:

54. The use or product according to point 53 here above wherein theIFN-beta is Rebif® (Serono).

In another embodiment, the invention provides:

55. The use or product according to any one of points 52 to 54 hereabove wherein the IFN-beta is administered systemically.

In another embodiment, the invention provides:

56. The use or product according to point 55 here above wherein theIFN-beta is administered subcutaneously or intramuscularly.

In another embodiment, the invention provides:

57. The use or product according to point 56 here above wherein theIFN-beta is dosed at least at 44 mcg subcutaneously per administration.

In another embodiment, the invention provides:

58. The use or product according to point 56 here above wherein theIFN-beta regimen is selected from the group consisting of: 12 MIU (44mcg) of IFN-beta three times a week, 12 MIU (44 mcg) daily, 24 MIU (88mcg) three times a week and 24 MIU (88 mcg) daily.

In another embodiment, the invention provides:

59. The use or product according to point 56 here above wherein theIFN-beta used is Rebif® (Serono) and is administered at 44 mcgsubcutaneously three times a week.

In another embodiment, the invention provides:

60. The use or product according to any one of points 1 to 59 here abovewherein the conventional therapy is selected from the group consistingof: treatment with beta interferon, treatment with Glatimarer Acetate(Copaxone®, Teva), treatment with natalizumab (Tysabri®, Biogen/Elan),and treatment with Mitoxantrone (Novantrone®, Serono).

In another embodiment, the invention provides:

61. The use or product according to point 60 here above wherein theconventional therapy is treatment with beta interferon, preferablytreatment with Betaseron® (Berlex/Schering AG); Avonex® (Biogen); orRebif® (Serono).

In another embodiment, the invention provides:

62. The use or product according to point 61 here above wherein theconventional therapy is a treatment with Rebif® (Serono).

In another embodiment, the invention provides:

63. The use or product according to point 60 or 61 here above whereinthe patients to be treated are refractory to one, two, three or four ofthe conventional therapies.

In another embodiment, the invention provides:

64. The use or product according to any one of points 1 to 63 here abovewherein the refractory patients to be treated have experienced at leastone relapse in spite of receiving at least one conventional therapy.

In another embodiment, the invention provides:

65. The use or product according to point 64 here above wherein the atleast one relapse occurred during the year prior the beginning of thetreatment according to any of the preceding claims.

In another embodiment, the invention provides:

66. The use or product according to point 65 here above wherein thepatients to be treated have experienced at least one relapse during theyear preceding the beginning of the treatment according to any of thepreceding claims and have been treated with Rebif® (Serono), inparticular 12 MIU (44 mcg) of Rebif® three times a week.

In another embodiment, the invention provides:

67. The use or product according to any of the points 1 to 66 here abovewherein the refractory patients to be treated have acquired enhancedlesion number or enhanced brain lesion volume in the CNS as detectedusing methods such as MRI technique, in spite of receiving at least oneconventional therapy.

In another embodiment, the invention provides:

68. The use or product according to point 67 here above wherein theenhanced lesion number or enhanced brain lesion volume occurred duringthe year prior the beginning of the treatment according to any of thepreceding claims.

In another embodiment, the invention provides:

69. The use or product according to claim 68 here above wherein thepatients to be treated have acquired enhanced lesion number or enhancedbrain lesion volume in the CNS during the year preceding the beginningof the treatment according to any of the preceding claims and have beentreated with Rebif® (Serono), in particular 12 MIU (44 mcg) of Rebif®three times a week.

In another embodiment, the invention provides:

70. The use or product according to any one of points 1 to 69 here abovewherein the refractory patients to be treated have experienced at leastone relapse and develop increasing disability because of progressiveforms of the disease.

In another embodiment, the invention provides:

71. The use or product according to any one of points 1 to 70 here abovewherein the refractory patients to be treated are suffering fromworsening MS, in particular secondary progressive, progressive remittingor worsening relapsing-remitting MS.

DETAILED DESCRIPTION OF THE INVENTION Definitions

The term “multiple sclerosis” within the meaning of the presentinvention may be defined as in the DSM-IV classification (Diagnosis andStatistical Manual of Inflammatory CNS Disorders, Fourth Edition,American Psychiatric Association, Washington D.C., 1994).

The “total dose” or “cumulative dose” refers to the total dose ofCladribine administered during the treatment, i.e. the dose reached atthe end of the treatment that is calculated by adding the daily doses.For example, the total dose of Cladribine corresponding to a treatmentof 0.7 mg/kg Cladribine per day during 5 days is 3.5 mg/kg or the totaldose of Cladribine corresponding to a treatment of 0.35 mg/kg Cladribineper day during 5 days is 1.7 mg/kg.

“The total effective dose” or “cumulative effective dose” refers to thebioavailable dose of Cladribine after a given administration period,i.e. the bioavailable dose reached at the end of the treatment that iscalculated by adding the daily doses reduced by the bioavailabilitycoefficient. For example, the total effective dose of Cladribinecorresponding to a treatment of 0.7 mg/kg Cladribine per day during 5days wherein the bioavailability of Cladribine is of about 40% is 1.4mg/kg or the total effective dose of Cladribine corresponding to atreatment of 0.35 mg/kg Cladribine per day during 5 days wherein thebioavailability of Cladribine is of about 40% is 0.7 mg/kg.

Typically, the bioavailability of Cladribine or of a Cladribineformulation used in the context of this invention is from about 30% toabout 90%, preferably from about 40% to about 60%, such as about 50%.

“A week” refers to a period of time of about 5, about 6 or about 7 days.

“A month” refers to a period of time of about 28, about 29, about 30 orabout 31 days.

“Treatment” comprises the sequential succession of an “inductiontreatment” and at least a “maintenance treatment”. Typically, atreatment according to the invention comprises an “induction treatment”and about one or about two or about three maintenance treatments.

Typically, a treatment according to the invention is of about 2 years(about 24 months) or about 3 years (about 36 months) or about 4 years(about 48 months).

An “Induction Treatment” consists in the sequential succession of (1) aninduction period wherein the Cladribine or the Cladribine pharmaceuticalpreparation of the invention is orally administered and (ii) aCladribine-free period. An induction period lasts up to about 4 monthsor up to about 3 month or up to about 2 months. For example, aninduction period lasts for about 2 to about 4 months. An inductionperiod consists in the oral administration of Cladribine or apharmaceutical preparation thereof during about 1 to about 7 days eachmonth.

A “Cladribine-free period” is a period wherein no Cladribine isadministered to the patient. During a Cladribine-free period, thepatient can be free of any administration or be dosed with aplacebo-pill or another drug except. A Cladribine-free period lasts upto about 10 months or up to 9 months or up to about 8 months. Forexample, a Cladribine-free period lasts from about 8 to about 10 months,typically at least of about 8 months.

A “Maintenance Treatment” consists in the sequential succession of (1) amaintenance period wherein the Cladribine or the Cladribinepharmaceutical preparation of the invention is orally administered at alower or equal dose than the Cladribine dose orally administered duringthe induction treatment and (ii) a Cladribine-free period. A maintenanceperiod lasts for up to about 4 months, or up to about 3 months, or up toabout 2 months, preferably up to about 2 months. For example, amaintenance period lasts for about 2 to about 4 months, preferably forabout 2 months. A maintenance period consists in the oral administrationof Cladribine or of a pharmaceutical preparation thereof during about 1to about 7 days each month.

Within the context of this invention, the beneficial effect, includingbut not limited to an attenuation, reduction, decrease or diminishing ofthe pathological development after onset of the disease, may be seenafter one or more “treatments”, after an “induction treatment”, after a“maintenance treatment” or during a Cladribine-free period.

“Daily dose” refers to the total dose of Cladribine orally administeredto the patient each day of administration. The daily dose can be reachedthrough a single or several administrations per day, such as for exampleonce a day, twice a day or three times a day.

The dosage administered, as single or multiple doses, to an individualwill vary depending upon a variety of factors, including pharmacokineticproperties, patient conditions and characteristics (sex, age, bodyweight, health, size), extent of symptoms, concurrent treatments,frequency of treatment and the effect desired.

Patients suffering from MS can be defined for example as havingclinically definite or laboratory-definite MS according to Schumacher orPoser criteria (Schumacher et al., 1965, Ann. NY Acad. Sci. 1965;122:552-568; Poser et al., 1983, Ann. Neurol. 13(3): 227-31).

“Relapses” involve neurologic problems that occur over a short period,typically days but sometimes as short as hours or even minutes. Theseattacks most often involve motor, sensory, visual or coordinationproblems early in the disease. Later, bladder, bowel, sexual andcognitive problems may be shown. Sometimes the attack onset occurs overseveral weeks. Typical MS relapse involves a period of worsening, withdevelopment of neurological deficits, then a plateau, in which thepatient is not getting any better but also not getting any worsefollowed by a recovery period. Recovery usually begins within a fewweeks.

“Efficacy” of a treatment according to the invention can be measuredbased on changes in the course of disease in response to a use accordingto the invention. For example, treatment of MS efficacy can be measuredby the frequency of relapses in RRMS and the presence or absence of newlesions in the CNS as detected using methods such as MRI technique(Miller et al., 1996, Neurology, 47(Suppl 4): S217; Evans et al., 1997,Ann. Neurology, 41:125-132).

The observation of the reduction and/or suppression of MRI T₁gadolinium-enhanced lesions (thought to represent areas of activeinflammation) gives a primary efficacy variable.

Secondary efficacy variables include MRI T₁ enhanced brain lesionvolume, MRI T₁ enhanced lesion number, MRI T₂ lesion volume (thought torepresent total disease burden, i.e. demyelination, gliosis,inflammation and axon loss), MRI T₁ enhanced hypointense lesion volume(thought to represent primarily demyelination and axon loss),time-to-progression of MS, frequency and severity of exacerbations andtime-to-exacerbation, Expanded Disability Status Scale score and ScrippsNeurologic Rating Scale (SNRS) score (Sipe et al., 1984, Neurology, 34,1368-1372). Methods of early and accurate diagnosis of multiplesclerosis and of following the disease progression are described inMattson, 2002, Expert Rev. Neurotherapeutics, 319-328.

Degree of disability of MS patients can be for example measured byKurtzke Expanded Disability Status Scale (EDSS) score (Kurtzke, 1983,Neurology, 33, 1444-1452). Typically a decrease in EDSS scorecorresponds to an improvement in the disease and conversely, an increasein EDSS score corresponds to a worsening of the disease.

Cladribine (2-CdA)

2-CdA and its pharmacologically acceptable salts may be used in thepractice of this invention.

Cladribine can be formulated in any pharmaceutical preparation suitablefor oral administration. Representative oral formulations of 2-CdA aredescribed in (WO 96/19230; WO 96/19229; U.S. Pat. Nos. 6,194,395;5,506,214; WO 2004/087100; WO 2004/087101), the contents of which areincorporated herein by reference. Examples of ingredients for oralformulations are given below.

Processes for preparing 2-CdA are well known in the art. For example,the preparation of 2-CdA is described in (EP 173,059; WO 04/028462; WO04/028462; U.S. Pat. No. 5,208,327; WO 00/64918) and Robins et al., J.Am. Chem. Soc., 1984, 106: 6379. Alternatively, pharmaceuticalpreparations of 2-CdA may be purchased from Bedford Laboratories,Bedford, Ohio.

Oral administration of Cladribine may be in capsule, tablet, oralsuspension, or syrup form. The tablet or capsules may contain from about3 to 500 mg of Cladribine. Preferably they may contain about 3 to about10 mg of Cladribine, more preferably about 3, about 5 or about 10 mg ofCladribine. The capsules may be gelatin capsules and may contain, inaddition to Cladribine in the quantity indicated above, a smallquantity, for example less than 5% by weight, magnesium stearate orother excipient. Tablets may contain the foregoing amount of thecompound and a binder, which may be a gelatin solution, a starch pastein water, polyvinyl polyvinyl alcohol in water, etc. with a typicalsugar coating.

In a preferred embodiment of the present invention, Cladribine isformulated in tablets. Preferably said tablets contain 3 mg or 10 mg of2-CdA. Even more preferably said tablets are the one disclosed in table2 here below (3 mg or 10 mg 2-CdA per tablet).

Compositions of Cladribine

Compositions of this invention may further comprise one or morepharmaceutically acceptable additional ingredient(s) such as alum,stabilizers, antimicrobial agents, buffers, coloring agents, flavoringagents, adjuvants, and the like.

Compositions of this invention may be in the form of tablets or lozengesformulated in a conventional manner. For example, tablets and capsulesfor oral administration may contain conventional excipients including,but not limited to, binding agents, fillers, lubricants, disintegrantsand wetting agents. Binding agents include, but are not limited to,syrup, accacia, gelatin, sorbitol, tragacanth, mucilage of starch andpolyvinylpyrrolidone. Fillers include, but are not limited to, lactose,sugar, microcrystalline cellulose, maize starch, calcium phosphate, andsorbitol. Lubricants include, but are not limited to, magnesiumstearate, stearic acid, talc, polyethylene glycol, and silica.Disintegrants include, but are not limited to, potato starch and sodiumstarch glycollate. Wetting agents include, but are not limited to,sodium lauryl sulfate. Tablets may be coated according to methods wellknown in the art.

Compositions of this invention may also be liquid formulationsincluding, but not limited to, aqueous or oily suspensions, solutions,emulsions, syrups, and elixirs. The compositions may also be formulatedas a dry product for constitution with water or other suitable vehiclebefore use. Such liquid preparations may contain additives including,but not limited to, suspending agents, emulsifying agents, nonaqueousvehicles and preservatives. Suspending agent include, but are notlimited to, sorbitol syrup, methyl cellulose, glucose/sugar syrup,gelatin, hydroxyethylcellulose, carboxymethyl cellulose, aluminumstearate gel, and hydrogenated edible fats. Emulsifying agents include,but are not limited to, lecithin, sorbitan monooleate, and acacia.Nonaqueous vehicles include, but are not limited to, edible oils, almondoil, fractionated coconut oil, oily esters, propylene glycol, and ethylalcohol. Preservatives include, but are not limited to, methyl or propylp-hydroxybenzoate and sorbic acid.

Interferon-Beta (IFN-Beta or IFN-b),

According to the present invention, Cladribine is administered incombination with a therapeutically effective amount of IFN-beta.IFN-beta is administered prior to, simultaneously or sequentially withCladribine. Active agents that are administered simultaneously withother therapeutic agents can be administered in the same or differentcompositions and in the same or different routes of administration.

The term “interferon-beta” (IFN-beta or IFN-b), as used in the presentinvention, is intended to include human fibroblast interferon, which maybe native, i.e. purified from a natural source, or obtained by DNArecombinant techniques from prokaryotic sources (e.g. Escherichia coli,E. coli) or from eukaryotic host cells, e.g. from yeast or mammaliancells. Mammalian cells such as Chinese hamster ovary cells (CHO) orhuman cells are a preferred host for production of recombinant IFN-beta.The IFN-beta may be glycosylated or non-glycosylated. If IFN-beta, usedin accordance with the present invention, is non-glycosylated (e.g.produced in E. coli), it is preferred to administer higher amounts ofIFN-beta in order to obtain a biological or pharmacological effectcomparable to that of glycosylated IFN-beta. For instance, an amount ofnon-glycosylated IFN-beta that is about 10 times higher than the amountof glycosylated IFN-beta is preferably administered in order to obtaincomparable activities.

The term “interferon-beta”, as used herein, also encompasses functionalderivatives, muteins, analogs, and fragments, or fusion proteins ofIFN-beta. Thus, the terms “interferon (IFN)” and “interferon-beta(IFN-beta)”, as used herein, are intended to include fibroblastinterferon in particular of human origin, as obtained by isolation frombiological fluids or as obtained by DNA recombinant techniques fromprokaryotic or eukaryotic host cells, as well as its salts, functionalderivatives, variants, analogs and active fragments. The use ofinterferon of human origin is preferred in accordance with the presentinvention.

In one embodiment of the present invention, the interferon-beta proteinused is interferon-beta 1a, such as for example, Avonex® (Biogen) orRebif® (Serono). In another embodiment of the present invention theinterferon-beta protein is interferon-beta 1b, such as for example,Betaseron® (Berlex/Schering AG).

Preferably, the IFN-beta to be used in the frame of the presentinvention is Betaseron® (Berlex/Schering AG); Avonex® (Biogen); orRebif® (Serono). Even preferred IFN-beta, is Rebif® (Serono).

Rebif® (interferon beta-1a) is a purified 166 amino acid glycoproteinwith a molecular weight of approximately 22,500 daltons. It is producedby recombinant DNA technology using genetically engineered ChineseHamster Ovary cells into which the human interferon beta gene has beenintroduced. The amino acid sequence of Rebif® is identical to that ofnatural fibroblast derived human interferon beta. Natural interferonbeta and interferon beta-1a (Rebif®) are glycosylated with eachcontaining a single N-linked complex carbohydrate moiety.

Using a reference standard calibrated against the World HealthOrganization natural interferon beta standard (Second InternationalStandard for Interferon, Human Fibroblast GB 23 902 531), Rebif® has aspecific activity of approximately 270 million international units (MIU)of antiviral activity per mg of interferon beta-1a determined in an invitro cytopathic effect bioassay using WISH cells and VesicularStomatitis virus.

Conversion table for MIU and mcg of IFN-beta MIU 3 12 18 24 mcg 11 44 6688

Rebif® 44 mcg contains approximately 12 MIU of antiviral activity usingthis method.

Rebif® (recombinant human interferon-beta) is the latest development ininterferon therapy for multiple sclerosis (MS) and represents asignificant advance in treatment. Rebif® is interferon (IFN)-beta 1a,produced from mammalian cell lines. It was established that interferonbeta-1a given subcutaneously three times per week is efficacious in thetreatment of Relapsing-Remitting Multiple Sclerosis (RRMS). Interferonbeta-1a can have a positive effect on the long-term course of MS byreducing number and severity of relapses and reducing the burden of thedisease and disease activity as measured by Mill.

In accordance with the present invention, where IFN-beta is recombinantIFN-beta 1b produced in E. Coli, commercially available under thetrademark Betaseron, it may preferably be administered subcutaneouslyevery second day at a dosage of about of 250 to 300 mcg or 8 MIU to 9.6MIU per person.

In accordance with the present invention, where IFN-beta is recombinantIFN-beta 1a, produced in Chinese Hamster Ovary cells (CHO cells),commercially available under the trademark Avonex, it may preferably beadministered intra-muscularly once a week at a dosage of about of 30 mcgto 33 mcg or 6 MIU to 6.6 MIU per person.

In accordance with the present invention, when IFN-beta is recombinantIFN-beta 1a, produced in Chinese Hamster Ovary cells (CHO cells),commercially available under the trademark Rebif, it may preferably beadministered subcutaneously three times a week (TIW) at a dosage of 22to 44 mcg or 6 MIU to 12 MIU per person. Preferably, a dosage of 44 mcgor 12 MIU per application is chosen.

IFN-beta proteins according to the present invention may includefunctional derivatives, variants and muteins of IFN-beta.

“Functional derivatives” as used herein cover derivatives of IFN-beta,and its variants or muteins and fused proteins, which may be preparedfrom the functional groups which occur as side chains on the residues orthe N or C terminal groups, by means known in the art. These functionalderivatives are included in the invention as long as they remainpharmaceutically acceptable, i.e. they do not destroy the activity ofthe protein, which is substantially similar to, or better than, theactivity of IFN-beta, and do not confer toxic properties on compositionscontaining it.

These derivatives may, for example, include polyethylene glycol sidechains, which may improve other properties of the protein, such as thestability, half-life, bioavailability, tolerance by the human body, orimmunogenicity. To achieve this goal, IFN-beta may be linked e.g. toPolyethlyenglycol (PEG). PEGylation may be carried out by known methods,described in WO 92/13095, for example. In particular, PEG-IFN can beprepared in accordance with the teaching of WO 99/55377.

Therefore, in a preferred embodiment, the functional derivative ofIFN-beta comprises at least one moiety attached to one or morefunctional groups, which occur as one or more side chains on the aminoacid residues. An embodiment in which the moiety is a polyethyleneglycol (PEG) moiety is highly preferred. In accordance with the presentinvention, several PEG moieties may also be attached to the IFN-beta.

Other derivatives include a modified interferon-beta protein, such as along-acting form interferon-beta. In particular, the long-actinginterferon-beta may be selected from pegylated interferon-beta,interferon-beta-HAS fusion proteins, and interferon-beta-Fc-fusionproteins.

Other derivatives include aliphatic esters of the carboxyl groups,amides of the carboxyl groups by reaction with ammonia or with primaryor secondary amines, N acyl derivatives of free amino groups of theamino acid residues formed with acyl moieties (e.g. alkanoyl orcarbocyclic aroyl groups) or O acyl derivatives of free hydroxyl groups(for example that of seryl or threonyl residues) formed with acylmoieties.

“Variants” or “muteins”, as used in the name of the present invention,refer to analogs of IFN-beta, in which one or more of the amino acidresidues of natural IFN-beta are replaced by different amino acidresidues, or are deleted, or one or more amino acid residues are addedto the natural sequence IFN-beta, without diminishing considerably theactivity of the resulting products as compared with the wild typeIFN-beta. These muteins are prepared by known synthesis and/or bysite-directed mutagenesis techniques, or any other known techniquesuitable therefor.

The “variant” or “mutein” in accordance with the present inventioninclude proteins encoded by a nucleic acid, such as DNA or RNA, whichhybridizes to DNA or RNA encoding IFN-beta as disclosed e.g. in U.S.Pat. No. 4,738,931 under stringent conditions. The term “stringentconditions” refers to hybridization and subsequent washing conditions,which those of ordinary skill in the art conventionally refer to as“stringent”. See Ausubel et al., Current Protocols in Molecular Biology,Interscience, N.Y., §§ 6.3 and 6.4 (1987, 1992). Without limitation,examples of stringent conditions include washing conditions 12-20° C.below the calculated Tm of the hybrid under study in, e.g., 2×SSC and0.5% SDS for 5 minutes, 2×SSC and 0.1% SDS for 15 minutes; 0.1×SSC and0.5% SDS at 37° C. for 30 60 minutes and then, a 0.1×SSC and 0.5% SDS at68° C. for 30 60 minutes. Those of ordinary skill in this art understandthat stringency conditions also depend on the length of the DNAsequences, oligonucleotide probes (such as 10-40 bases) or mixedoligonucleotide probes. If mixed probes are used, it is preferable touse tetramethyl ammonium chloride (TMAC) instead of SSC. See Ausubel,supra.

Identity reflects a relationship between two or more polypeptidesequences or two or more polynucleotide sequences, determined bycomparing the sequences. In general, identity refers to an exactnucleotide to nucleotide or amino acid to amino acid correspondence ofthe two polynucleotides or two polypeptide sequences, respectively, overthe length of the sequences being compared.

For sequences where there is not an exact correspondence, a “% identity”may be determined. In general, the two sequences to be compared arealigned to give a maximum correlation between the sequences. This mayinclude inserting “gaps” in either one or both sequences, to enhance thedegree of alignment. A % identity may be determined over the wholelength of each of the sequences being compared (so-called globalalignment), that is particularly suitable for sequences of the same orvery similar length, or over shorter, defined lengths (so-called localalignment), that is more suitable for sequences of unequal length.

Methods for comparing the identity and homology of two or more sequencesare well known in the art. Thus for instance, programs available in theWisconsin Sequence Analysis Package, version 9.1 (Devereux J et al.,1984), for example the programs BESTFIT and GAP, may be used todetermine the % identity between two polynucleotides and the % identityand the % homology between two polypeptide sequences. BESTFIT uses the“local homology” algorithm of Smith and Waterman (1981) and finds thebest single region of similarity between two sequences. Other programsfor determining identity and/or similarity between sequences are alsoknown in the art, for instance the BLAST family of programs (Altschul SF et al, 1990, Altschul S F et al, 1997, accessible through the homepage of the NCBI at See Worldwide Website ncbi.nlm.nih.gov) and FASTA(Pearson W R, 1990).

The “variant” or “mutein” in accordance with the present inventioninclude proteins having a sequence of amino acids sufficientlyduplicative of that of IFN-beta, such as to have substantially similaractivity to IFN-beta. A functional assay for evaluating whether anyvariant or mutein has a similar activity as IFN-beta is e.g. the assaymeasuring the activity of interferon on the cytopathic effect ofvesicular stomatitis virus in WISH cells, e.g. described by Youcefi etal., 1985. Thus, it can be determined whether any given mutein hassubstantially the same activity as IFN-beta by means of routineexperimentation. In a preferred embodiment, any such variant or muteinhas at least 40% identity or homology with the sequence of IFN-beta asdisclosed e.g. in U.S. Pat. No. 4,738,931. More preferably, it has atleast 50%, at least 60%, at least 70%, at least 80% or, most preferably,at least 90% identity or homology thereto.

Muteins of IFN-beta, which can be used in accordance with the presentinvention, or nucleic acid coding thereof, include a finite set ofsubstantially corresponding sequences as substitution peptides orpolynucleotides which can be routinely obtained by one of ordinary skillin the art, without undue experimentation, based on the teachings andguidance presented herein.

Preferred changes for muteins in accordance with the present inventionare what are known as “conservative” substitutions. Conservative aminoacid substitutions of IFN-beta polypeptides may include synonymous aminoacids within a group which have sufficiently similar physicochemicalproperties that substitution between members of the group will preservethe biological function of the molecule (Grantham, 1974). It is clearthat insertions and deletions of amino acids may also be made in theabove-defined sequences without altering their function, particularly ifthe insertions or deletions only involve a few amino acids, e.g., underthirty, and preferably under ten, and do not remove or displace aminoacids which are critical to a functional conformation, e.g., cysteineresidues. Proteins and muteins produced by such deletions and/orinsertions come within the purview of the present invention.

Preferably, the synonymous amino acid groups are those defined in TableI. More preferably, the synonymous amino acid groups are those definedin Table II; and most preferably the synonymous amino acid groups arethose defined in Table III.

TABLE I Preferred Groups of Synonymous Amino Acids Amino Acid SynonymousGroup Ser Ser, Thr, Gly, Asn Arg Arg, Gln, Lys, Glu, His Leu Ile, Phe,Tyr, Met, Val, Leu Pro Gly, Ala, Thr, Pro Thr Pro, Ser, Ala, Gly, His,Gln, Thr Ala Gly, Thr, Pro, Ala Val Met, Tyr, Phe, Ile, Leu, Val GlyAla, Thr, Pro, Ser, Gly Ile Met, Tyr, Phe, Val, Leu, Ile Phe Trp, Met,Tyr, Ile, Val, Leu, Phe Tyr Trp, Met, Phe, Ile, Val, Leu, Tyr Cys Ser,Thr, Cys His Glu, Lys, Gln, Thr, Arg, His Gln Glu, Lys, Asn, His, Thr,Arg, Gln Asn Gln, Asp, Ser, Asn Lys Glu, Gln, His, Arg, Lys Asp Glu,Asn, Asp Glu Asp, Lys, Asn, Gln, His, Arg, Glu Met Phe, Ile, Val, Leu,Met Trp Trp

TABLE II More Preferred Groups of Synonymous Amino Acids Amino AcidSynonymous Group Ser Ser Arg His, Lys, Arg Leu Leu, Ile, Phe, Met ProAla, Pro Thr Thr Ala Pro, Ala Val Val, Met, Ile Gly Gly Ile Ile, Met,Phe, Val, Leu Phe Met, Tyr, Ile, Leu, Phe Tyr Phe, Tyr Cys Cys, Ser HisHis, Gln, Arg Gln Glu, Gln, His Asn Asp, Asn Lys Lys, Arg Asp Asp, AsnGlu Glu, Gln Met Met, Phe, Ile, Val, Leu Trp Trp

TABLE III Most Preferred Groups of Synonymous Amino Acids Amino AcidSynonymous Group Ser Ser Arg Arg Leu Leu, Ile, Met Pro Pro Thr Thr AlaAla Val Val Gly Gly Ile Ile, Met, Leu Phe Phe Tyr Tyr Cys Cys, Ser HisHis Gln Gln Asn Asn Lys Lys Asp Asp Glu Glu Met Met, Ile, Leu Trp Met

Examples of production of amino acid substitutions in proteins which canbe used for obtaining muteins of IFN-beta for use in the presentinvention include any known method steps, such as presented in U.S. Pat.Nos. 4,959,314, 4,588,585 and 4,737,462, to Mark et al; U.S. Pat. No.5,116,943 to Koths et al., U.S. Pat. No. 4,965,195 to Namen et al; U.S.Pat. No. 4,879,111 to Chong et al; and U.S. Pat. No. 5,017,691 to Lee etal; and lysine substituted proteins presented in U.S. Pat. No. 4,904,584(Shaw et al).

The “variant” or “mutein” in accordance with the present inventioninclude also the so-called “consensus interferons”. “Consensusinterferons” are non-naturally occurring variants of IFN (U.S. Pat. No.6,013,253). Consensus interferons may also be used according to theinvention.

In accordance with the present invention, a salt of IFN-beta may also beused for treatment of Multiple Sclerosis.

The term “salts” herein refers to both salts of carboxyl groups and toacid addition salts of amino groups of the proteins described above oranalogs thereof. Salts of a carboxyl group may be formed by means knownin the art and include inorganic salts, for example, sodium, calcium,ammonium, ferric or zinc salts, and the like, and salts with organicbases as those formed, for example, with amines, such astriethanolamine, arginine or lysine, piperidine, procaine and the like.Acid addition salts include, for example, salts with mineral acids, suchas, for example, hydrochloric acid or sulfuric acid, and salts withorganic acids, such as, for example, acetic acid or oxalic acid. Ofcourse, any such salts must retain the biological activity of IFN-beta,which may be measured e.g. in the bioassay described above.

The term “fused protein” refers to a polypeptide comprising IFN-beta, ora variant or mutein or fragment thereof, fused with another protein,which, e.g., has an extended residence time in body fluids. IFN-beta maythus be fused to another protein, polypeptide or the like, e.g., animmunoglobulin or a fragment thereof.

Therefore, in a further embodiment, IFN-beta comprises an immunoglobulinfusion, i.e. IFN-beta is a fused protein comprising all or part ofIFN-beta fused to all or a portion of an immunoglobulin. Methods formaking immunoglobulin fusion proteins are well known in the art, such asthe ones described in WO 01/03737, for example. The person skilled inthe art will understand that the resulting fusion protein of theinvention retains the biological activity of IFN-beta. The fusion may bedirect, or via a short linker peptide which can be as short as 1 to 3amino acid residues in length or longer, for example, 13 amino acidresidues in length. Said linker may be a tripeptide of the sequenceE-F-M (Glu-Phe-Met), for example, or a 13-amino acid linker sequencecomprising Glu-Phe-Gly-Ala-Gly-Leu-Val-Leu-Gly-Gly-Gln-Phe-Met (SEQ IDNO: 1), or a Gly-Ser rich linker introduced between the IFN-betasequence and the sequence derived from an immunoglobulin sequence. Theresulting fusion protein has improved properties, such as an extendedresidence time in body fluids (half-life), increased specific activity,increased expression level, or the purification of the fusion protein isfacilitated.

In a further preferred embodiment, IFN-beta is fused to the constantregion of an Ig molecule, often called the Fc part of theimmunoglobulin. Preferably, it is fused to heavy chain regions, like theCH2 and CH3 domains of human IgG1, for example. Other isoforms of Igmolecules are also suitable for the generation of fusion proteinsaccording to the present invention, such as isoforms IgG2, IgG3 or IgG4,or other Ig classes, like IgM or IgA, for example. Fusion proteins maybe monomeric or multimeric, hetero- or homomultimeric. Methods ofpreparing immunoblobulin fusion proteins are known in the art, e.g. fromEP 526 452 or from U.S. Pat. No. 5,155,027. Ig fusion proteinscomprising IFN-beta moieties are described e.g. in EP 227 110, U.S. Pat.No. 5,541,087, WO 97/24137 or WO 00/23472.

A “fragment” according to the present invention refers to any subset ofIFN-beta, that is, a shorter peptide, which retains the desiredbiological activity as measurable e.g. in the bioassay described above.Fragments may readily be prepared by removing amino acids from eitherend of the molecule and testing the resultant for its properties as areceptor agonist. Proteases for removing one amino acid at a time fromeither the N-terminal or the C-terminal of a polypeptide are known, andso determining fragments, which retain the desired biological activity,may be determined e.g. in the test described by Youcefi et al., 1985,and involves only routine experimentation.

While the present invention provides recombinant methods for making theabove-defined derivatives, these derivatives may also be made byconventional protein synthesis methods, which are well known to thoseskilled in the art.

IFN-beta, or a variant/mutein, functional derivative, active fragment orfusion protein thereof having IFN-beta activity, is preferablyadministered systemically, and preferably subcutaneously orintramuscularly. Intradermal, transdermal (e.g. in slow releaseformulations), intravenous, oral, intracranial, epidural, topical,rectal, and intranasal routes are also within the present invention.

Any other therapeutically efficacious route of administration may alsobe used, for example absorption through epithelial or endothelialtissues or by gene therapy wherein a DNA molecule encoding the IFN-betais administered to the patient (e.g. via a vector), which causesIFN-beta to be expressed and secreted in vivo.

IFN-beta may be formulated as a pharmaceutical composition, i.e.together with a pharmaceutically acceptable carrier, excipients or thelike. The definition of “pharmaceutically acceptable” is meant toencompass any carrier, which does not interfere with effectiveness ofthe biological activity of the active ingredient and that is not toxicto the host to which it is administered. For example, for parenteraladministration, the active protein(s) may be formulated in a unit dosageform for injection in vehicles such as saline, dextrose solution, serumalbumin and Ringer's solution.

In accordance with the present invention, when IFN-beta is recombinantIFN-beta 1a, produced in Chinese Hamster Ovary cells (CHO cells),commercially available under the trademark Rebif, it may preferably beformulated as HSA (Human Serum Albumin)-free formulation (containingrecombinant interferon beta-1a plus excipients) as disclosed inWO2004/096263.

The dosage administered, as single or multiple doses, to an individualmay vary depending upon a variety of factors, including IFN-betapharmacokinetic properties, the route of administration, patientconditions and characteristics (sex, age, body weight, health, size),extent of symptoms, concurrent treatments, frequency of treatment.Adjustment and manipulation of established dosage ranges may bedetermined by those skilled in the art.

In one embodiment of the present invention, the IFN-beta is dosed atleast at 44 mcg subcutaneously per administration. Preferred doses andregimens in accordance with the present invention are selected from thegroup consisting of: 12 MIU (44 mcg) of IFN-beta three times a week, 12MIU (44 mcg) daily, 24 MIU (88 mcg) three times a week, 24 MIU (88 mcg)daily. These doses are preferably administered subcutaneously. In oneparticularly preferred embodiment, the IFN-beta is dosed at 44 mcgsubcutaneously three times a week.

It is also preferred to administer IFN-beta at 100 mcg (about 27 MIU)once per week intramuscularly.

The daily doses may also be given in divided doses or in sustainedrelease form effective to obtain the desired results. Second orsubsequent administrations can be performed at a dosage which is thesame, less than or greater than the initial or previous doseadministered to the individual.

Patients

The patients to be treated according to the method of the presentinvention are patients suffering from multiple sclerosis, who arerefractory to at least one conventional therapy for MS.

Preferably the refractory patients are treated with a conventionaltherapy for MS, which is not clinically adequate to relieve one or moresymptoms associated with such disorder. Typically, such patients aresuffering from multiple sclerosis but are experiencing worsening orstagnation of the symptoms of the disease in spite of being treated forMS with such conventional therapy and require additional therapy toameliorate the symptoms associated with their disorder.

In an embodiment of the present invention, the conventional therapy isselected from the group consisting of: treatment with beta interferon,treatment with Glatimarer Acetate (Copaxone®, Teva), treatment withnatalizumab (Tysabri®, Biogen/Elan), or treatment with Mitoxantrone(Novantrone®, Serono). In a preferred embodiment, the conventionaltherapy is treatment with beta interferon, preferably treatment withBetaseron® (Berlex/Schering AG); Avonex® (Biogen); or Rebif® (Serono).In an even preferred embodiment, the conventional therapy is treatmentwith Rebif® (Serono).

In an embodiment of the present invention, the patients to be treatedaccording to the method of the present invention are refractory to one,two, three or four of the conventional therapies described herein.

In a particular embodiment, the refractory patients to be treated haveexperienced at least one relapse, in particular one, two, three, four orfive relapse, irrespective of disability progression, in spite ofreceiving at least one conventional therapy. Preferably, the at leastone relapse, in particular one, two, three, four or five relapse,occurred during the year prior the beginning of the treatment accordingto the present invention. In a particular embodiment, the patients to betreated have experienced at least one relapse, in particular one, two,three, four or five relapse, during the year preceding the beginning ofthe treatment of the present invention and have been treated with Rebif®(Serono), in particular 12 MIU (44 mcg) of Rebif® three times a week.

In a particular embodiment, the refractory patients to be treated haveexperienced at least one relapse, in particular one, two, three, four orfive relapse, and develop increasing disability because of progressiveforms of the disease, in spite of receiving at least one conventionaltherapy. Degree of disability of MS patients can be for example measuredby Kurtzke Expanded Disability Status Scale (EDSS) score (Kurtzke, 1983,Neurology, 33, 1444-1452). Typically a decrease in EDSS scorecorresponds to an improvement in the disease and conversely, an increasein EDSS score corresponds to a worsening of the disease. In a particularembodiment, the at least one relapse, in particular one, two, three,four or five relapse, occurred during the year prior the beginning ofthe treatment according to the present invention. In a particularembodiment, the patients to be treated have experienced at least onerelapse, in particular one, two, three, four or five relapse, during theyear preceding the beginning of the treatment of the present inventionand have been treated with Rebif® (Serono), in particular 12 MIU (44mcg) of Rebif® three times a week.

In a particular embodiment, the refractory patients to be treateddevelop increasing disability because of progressive forms of thedisease, in spite of receiving at least one conventional therapy. Degreeof disability of MS patients can be for example measured by KurtzkeExpanded Disability Status Scale (EDSS) score (Kurtzke, 1983, Neurology,33, 1444-1452). Typically a decrease in EDSS score corresponds to animprovement in the disease and conversely, an increase in EDSS scorecorresponds to a worsening of the disease. In a particular embodiment,the patients to be treated experienced an increase in their EDSS scoreof 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8 or8.5, in spite of receiving at least one conventional therapy.Preferably, the increase in EDSS score is of 0.5, 1, 1.5, 2, 2.5, 3,3.5, 4, 4.5 or 5 in spite of receiving at least one conventionaltherapy. Even more preferably, the increase in EDSS score is of 0.5, 1,1.5 or 2, 2.5 in spite of receiving at least one conventional therapy.Most preferably, the increase in EDSS score is of 0.5, 1 or 1.5(preferably 1) in spite of receiving at least one conventional therapy.In a preferred embodiment said increase in EDSS score occurred duringone, two, three, four, five, six, seven, eight or ten years prior thebeginning of the treatment according to the present invention.Preferably the increase in EDSS score occurred during one, two, three,four or five, years prior the beginning of the treatment according tothe present invention. Even more preferably, the increase in EDSS scoreoccurred during one, two or three years prior the beginning of thetreatment according to the present invention. Most preferably, theincrease in EDSS score occurred during one or two, preferably one, yearprior the beginning of the treatment according to the present invention.In a preferred embodiment of the present invention, the patients to betreated experienced increase in their EDSS score associated to at leastone relapse, in particular one, two, three, four, five, six, seven orten relapses, preferably one, two, three, four or five relapses, evenmore preferably one, two, or three relapses, most preferably one or two(preferably one) relapses. In a particular embodiment, the patients tobe treated have experienced increase in their EDSS score as disclosedhere above in spite of being treated with Rebif® (Serono), in particular12 MIU (44 mcg) of Rebif® three times a week.

In a particular embodiment, the refractory patients to be treated haveacquired enhanced lesion number or enhanced brain lesion volume in theCNS as detected using methods such as MRI technique (Miller et al.,1996, Neurology, 47(Suppl 4): S217; Evans et al., 1997, Ann. Neurology,41:125-132), in spite of receiving at least one conventional therapy. Ina particular embodiment, the enhanced lesion number or enhanced brainlesion volume occurred during the year prior the beginning of thetreatment according to the present invention. In a particularembodiment, the patients to be treated have acquired enhanced lesionnumber or enhanced brain lesion volume in the CNS during the yearpreceding the beginning of the treatment of the present invention andhave been treated with Rebif® (Serono), in particular 12 MIU (44 mcg) ofRebif® three times a week.

In an embodiment of the present invention, the refractory patients to betreated are suffering from worsening MS, in particular secondaryprogressive, progressive remitting or worsening relapsing-remitting MS,in spite of being treated by conventional therapy.

In an embodiment of the present invention, refractory patients to betreated according to the method of the present invention are patientssuffering from progressive relapsing multiple sclerosis (PRMS) orprimary progressive multiple sclerosis (PPMS).

In an embodiment of the invention, patients are selected from humanmales or females between 18 and 55 years age.

Combination Therapy of Oral Cladribine and Interferon-Beta (IFN-Beta orIFN-b) According to the Present Invention

According to the present invention, Cladribine is administered incombination with a therapeutically effective amount of IFN-beta.IFN-beta is administered prior to, simultaneously and/or sequentiallywith Cladribine. Active agents that are administered simultaneously withother therapeutic agents can be administered in the same or differentcompositions and in the same or different routes of administration.

An object of the present invention resides in the use of a combinationof Cladribine and IFN-beta for the manufacture of a medicament fortreating patients suffering from multiple sclerosis and who arerefractory to at least one conventional therapy for multiple sclerosis,wherein Cladribine is to be orally administered following the sequentialsteps below:

-   -   (i) An induction period wherein Cladribine is administered and        wherein the total dose of Cladribine reached at the end of the        induction period is from about 1.7 mg/kg to about 3.5 mg/kg;    -   (ii) A Cladribine-free period wherein no Cladribine is        administered;    -   (iii) A maintenance period wherein Cladribine is administered        and wherein the total dose of Cladribine administered during the        maintenance period is lower than or equal to the total dose of        Cladribine reached at the end of the induction period (i);    -   (iv) A Cladribine-free period wherein no Cladribine is        administered.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein the inductionperiod lasts up to about 4 months or up to about 3 months or up to about2 months.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein the inductionperiod lasts up to about 2 months.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein the inductionperiod lasts up to about 4 months.

In a preferred further embodiment, the invention provides the use of acombination of Cladribine and IFN-beta, as disclosed herein, wherein thetotal dose of Cladribine reached at the end of the induction period isabout 1.7 mg/kg, preferably 1.75 mg/kg. In a preferred embodiment, thetotal dose of Cladribine reached at the end of the induction period isabout 1.7 mg/kg, preferably 1.75 mg/kg, and the induction period lastsup to about 2 months.

In a further preferred embodiment, the invention provides the use of acombination of Cladribine and IFN-beta, as disclosed herein, wherein thetotal dose of Cladribine reached at the end of the induction period isabout 3.5 mg/kg, preferably 3.5 mg/kg. In a preferred embodiment, thetotal dose of Cladribine reached at the end of the induction period isabout 3.5 mg/kg, preferably 3.5 mg/kg, and the induction period lasts upto about 4 months.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein theCladribine-free period (ii) lasts up to about 10 months, or up to about9 months or up to about 8 months.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein theCladribine-free (ii) period lasts up to about 8 months.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein theCladribine-free (ii) period lasts at least about 8 months.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein theCladribine-free period (ii) lasts up to about 10 months.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein the combinedduration of the induction period (i) with the Cladribine-free period(ii) is about 1 year (about 12 months). Preferably the duration of theinduction period is about 4 months and the duration of theCladribine-free period (ii) is about 8 months, or the duration of theinduction period is about 3 months and the duration of theCladribine-free period (ii) is about 9 months, or the duration of theinduction period is about 2 months and the duration of theCladribine-free period (ii) is about 10 months.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein the combinedduration of the induction period (i) with the Cladribine-free period(ii) is about 1 year (about 12 months) and the total dose of Cladribinereached at the end of this year of treatment is about 1.7 mg/kg,preferably 1.75 mg/kg or about 3.5 mg/kg, preferably 3.5 mg/kg.Preferably the duration of the induction period is about 4 months andthe duration of the Cladribine-free period (ii) is about 8 months, orthe duration of the induction period is about 3 months and the durationof the Cladribine-free period (ii) is about 9 months, or the duration ofthe induction period is about 2 months and the duration of theCladribine-free period (ii) is about 10 months.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein theCladribine-free period (iv) lasts up to about 10 months, or up to about9 months or up to about 8 months.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein theCladribine-free (iv) period lasts up to about 10 months.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein theCladribine-free (iv) period lasts at least about 8 months.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein theCladribine-free periods (ii) and/or (iv) last between about 8 and about10 months.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein a placebo-pillis administered during the Cladribine-free period.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein theCladribine-free period is free of any administration.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein the maintenanceperiod lasts up to about 4 months, or up to about 3 months, or up toabout 2 months, preferably up to about 2 months.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein the total doseof Cladribine administered during the maintenance period (iii) is about1.7 mg/kg, preferably 1.75 mg/kg. In a further preferred embodiment, thetotal dose of Cladribine administered during the maintenance period isabout 1.7 mg/kg, preferably 1.75 mg/kg, and the maintenance period lastsup to about 2 months.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein the combinedduration of the maintenance period (iii) with the Cladribine-free period(iv) is about 1 year (about 12 months). Preferably the duration of themaintenance period (iii) is about 4 months and the duration of theCladribine-free period (iv) is about 8 months, or the duration of themaintenance period (iii) is about 3 months and the duration of theCladribine-free period (iv) is about 9 months. Even more preferably, theduration of the maintenance period (iii) is about 2 months and theduration of the Cladribine-free period (iv) is about 10 months.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein the combinedduration of the maintenance period (iii) with the Cladribine-free period(iv) is about 1 year (about 12 months) and the total dose of Cladribineadministered during this year of treatment is about 1.7 mg/kg,preferably 1.75 mg/kg. Preferably the duration of the maintenance period(iii) is about 4 months and the duration of the Cladribine-free period(iv) is about 8 months, or the duration of the maintenance period (iii)is about 3 months and the duration of the Cladribine-free period (iv) isabout 9 months. Even more preferably, the duration of the maintenanceperiod (iii) is about 2 months and the duration of the Cladribine-freeperiod (iv) is about 10 months.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein the combinedduration of the induction period (i), the Cladribine-free period (ii),the maintenance period (iii) and the Cladribine-free period (iv) isabout 2 years (about 24 months). In an embodiment, the duration of theinduction period is about 4 months, the duration of the Cladribine-freeperiod (ii) is about 8 months, the duration of the maintenance period(iii) is about 4 months and the duration of the Cladribine-free period(iv) is about 8 months. In another embodiment, the duration of theinduction period is about 4 months, the duration of the Cladribine-freeperiod (ii) is about 8 months, the duration of the maintenance period(iii) is about 3 months and the duration of the Cladribine-free period(iv) is about 9 months. In another embodiment, the duration of theinduction period is about 4 months, the duration of the Cladribine-freeperiod (ii) is about 8 months, the duration of the maintenance period(iii) is about 2 months and the duration of the Cladribine-free period(iv) is about 10 months. In another embodiment, the duration of theinduction period is about 3 months, the duration of the Cladribine-freeperiod (ii) is about 9 months, the duration of the maintenance period(iii) is about 4 months and the duration of the Cladribine-free period(iv) is about 8 months. In another embodiment, the duration of theinduction period is about 3 months, the duration of the Cladribine-freeperiod (ii) is about 9 months, the duration of the maintenance period(iii) is about 3 months and the duration of the Cladribine-free period(iv) is about 9 months. In another embodiment, the duration of theinduction period is about 3 months, the duration of the Cladribine-freeperiod (ii) is about 9 months, the duration of the maintenance period(iii) is about 2 months and the duration of the Cladribine-free period(iv) is about 10 months. In another embodiment, the duration of theinduction period is about 2 months, the duration of the Cladribine-freeperiod (ii) is about 10 months, the duration of the maintenance period(iii) is about 4 months and the duration of the Cladribine-free period(iv) is about 8 months. In another embodiment, the duration of theinduction period is about 2 months, the duration of the Cladribine-freeperiod (ii) is about 10 months, the duration of the maintenance period(iii) is about 3 months and the duration of the Cladribine-free period(iv) is about 9 months. In another embodiment, the duration of theinduction period is about 2 months, the duration of the Cladribine-freeperiod (ii) is about 10 months, the duration of the maintenance period(iii) is about 2 months and the duration of the Cladribine-free period(iv) is about 10 months.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein the combinedduration of the induction period (i) and the Cladribine-free period (ii)is about 1 year (12 months), the combined duration of the maintenanceperiod (iii) and the Cladribine-free period (iv) is about 1 year (about12 months), the total dose of Cladribine administered during the firstyear of treatment is about 1.7 mg/kg, preferably 1.75 mg/kg and thetotal dose of Cladribine administered during the second year oftreatment is about 1.7 mg/kg, preferably 1.75 mg/kg. In an embodiment,the duration of the induction period is about 4 months, the duration ofthe Cladribine-free period (ii) is about 8 months, the duration of themaintenance period (iii) is about 4 months and the duration of theCladribine-free period (iv) is about 8 months. In another embodiment,the duration of the induction period is about 4 months, the duration ofthe Cladribine-free period (ii) is about 8 months, the duration of themaintenance period (iii) is about 3 months and the duration of theCladribine-free period (iv) is about 9 months. In another embodiment,the duration of the induction period is about 4 months, the duration ofthe Cladribine-free period (ii) is about 8 months, the duration of themaintenance period (iii) is about 2 months and the duration of theCladribine-free period (iv) is about 10 months. In another embodiment,the duration of the induction period is about 3 months, the duration ofthe Cladribine-free period (ii) is about 9 months, the duration of themaintenance period (iii) is about 4 months and the duration of theCladribine-free period (iv) is about 8 months. In another embodiment,the duration of the induction period is about 3 months, the duration ofthe Cladribine-free period (ii) is about 9 months, the duration of themaintenance period (iii) is about 3 months and the duration of theCladribine-free period (iv) is about 9 months. In another embodiment,the duration of the induction period is about 3 months, the duration ofthe Cladribine-free period (ii) is about 9 months, the duration of themaintenance period (iii) is about 2 months and the duration of theCladribine-free period (iv) is about 10 months. In another embodiment,the duration of the induction period is about 2 months, the duration ofthe Cladribine-free period (ii) is about 10 months, the duration of themaintenance period (iii) is about 4 months and the duration of theCladribine-free period (iv) is about 8 months. In another embodiment,the duration of the induction period is about 2 months, the duration ofthe Cladribine-free period (ii) is about 10 months, the duration of themaintenance period (iii) is about 3 months and the duration of theCladribine-free period (iv) is about 9 months. In another embodiment,the duration of the induction period is about 2 months, the duration ofthe Cladribine-free period (ii) is about 10 months, the duration of themaintenance period (iii) is about 2 months and the duration of theCladribine-free period (iv) is about 10 months.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein the combinedduration of the induction period (i) and the Cladribine-free period (ii)is about 1 year (12 months), the combined duration of the maintenanceperiod (iii) and the Cladribine-free period (iv) is about 1 year (about12 months), the total dose of Cladribine administered during the firstyear of treatment is about 3.5 mg/kg, preferably 3.5 mg/kg and the totaldose of Cladribine administered during the second year of treatment isabout 1.7 mg/kg, preferably 1.75 mg/kg. In an embodiment, the durationof the induction period is about 4 months, the duration of theCladribine-free period (ii) is about 8 months, the duration of themaintenance period (iii) is about 4 months and the duration of theCladribine-free period (iv) is about 8 months. In another embodiment,the duration of the induction period is about 4 months, the duration ofthe Cladribine-free period (ii) is about 8 months, the duration of themaintenance period (iii) is about 3 months and the duration of theCladribine-free period (iv) is about 9 months. In another embodiment,the duration of the induction period is about 4 months, the duration ofthe Cladribine-free period (ii) is about 8 months, the duration of themaintenance period (iii) is about 2 months and the duration of theCladribine-free period (iv) is about 10 months. In another embodiment,the duration of the induction period is about 3 months, the duration ofthe Cladribine-free period (ii) is about 9 months, the duration of themaintenance period (iii) is about 4 months and the duration of theCladribine-free period (iv) is about 8 months. In another embodiment,the duration of the induction period is about 3 months, the duration ofthe Cladribine-free period (ii) is about 9 months, the duration of themaintenance period (iii) is about 3 months and the duration of theCladribine-free period (iv) is about 9 months. In another embodiment,the duration of the induction period is about 3 months, the duration ofthe Cladribine-free period (ii) is about 9 months, the duration of themaintenance period (iii) is about 2 months and the duration of theCladribine-free period (iv) is about 10 months. In another embodiment,the duration of the induction period is about 2 months, the duration ofthe Cladribine-free period (ii) is about 10 months, the duration of themaintenance period (iii) is about 4 months and the duration of theCladribine-free period (iv) is about 8 months. In another embodiment,the duration of the induction period is about 2 months, the duration ofthe Cladribine-free period (ii) is about 10 months, the duration of themaintenance period (iii) is about 3 months and the duration of theCladribine-free period (iv) is about 9 months. In another embodiment,the duration of the induction period is about 2 months, the duration ofthe Cladribine-free period (ii) is about 10 months, the duration of themaintenance period (iii) is about 2 months and the duration of theCladribine-free period (iv) is about 10 months.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein the steps (iii)to (iv) are repeated at least one, two or three times.

Another preferred embodiment of the present invention resides in the useof a combination of Cladribine IFN-beta for the manufacture of amedicament for treating patients suffering from multiple sclerosis andwho are refractory to at least one conventional therapy for multiplesclerosis, wherein Cladribine is to be orally administered following thesequential steps below:

-   -   (i) An induction period wherein Cladribine is administered and        wherein the total dose of Cladribine reached at the end of the        induction period is from about 1.7 mg/kg to about 3.5 mg/kg;    -   (ii) A Cladribine-free period wherein no Cladribine is        administered;    -   (iii) A maintenance period wherein Cladribine is administered        and wherein the total dose of Cladribine administered during the        maintenance period is lower than or equal to the total dose of        Cladribine reached at the end of the induction period (i)    -   (iv) A Cladribine-free period wherein no Cladribine is        administered;        wherein the induction period last up to about 4 months, or up to        about 3 months, or up to about 2 months; the Cladribine-free        period (ii) lasts up to about 10 months, or up to about 9        months, or up to about 8 months; the maintenance period (iii)        lasts up to about 2 months; the Cladribine-free period (iv)        lasts up to about 10 months; the total dose of Cladribine        administered during the maintenance period is about 1.7 mg/kg        and steps (iii) to (iv) are performed one, two or three times.

In another embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta for the manufacture of a medicament fortreating patients suffering from multiple sclerosis and who arerefractory to at least one conventional therapy for multiple sclerosis,wherein Cladribine is to be orally administered following the sequentialsteps below:

-   -   (i) An induction period wherein Cladribine is administered and        wherein the total effective dose of Cladribine reached at the        end of the induction period is from about 0.7 mg/kg to about 1.4        mg/kg;    -   (ii) A Cladribine-free period wherein no Cladribine is        administered;    -   (iii) A maintenance period wherein Cladribine is administered        and wherein the total effective dose of Cladribine administered        during the maintenance period (iii) is lower than or equal to        the total effective dose of Cladribine reached at the end of the        induction period (i);    -   (iv) A Cladribine-free period wherein no Cladribine is        administered.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta for the manufacture of a medicament fortreating patients suffering from multiple sclerosis and who arerefractory to at least one conventional therapy for multiple sclerosis,wherein Cladribine is to be orally administered following the sequentialsteps below:

-   -   (i) An induction period wherein Cladribine is administered and        wherein the total effective dose of Cladribine reached at the        end of the induction period is from about 0.7 mg/kg to about 1.4        mg/kg;    -   (ii) A Cladribine-free period wherein no Cladribine is        administered;    -   (iii) A maintenance period wherein Cladribine is administered        and wherein the total effective dose of Cladribine administered        during the maintenance period is lower than the total effective        dose of Cladribine reached at the end of the induction period        (i);    -   (iv) A Cladribine-free period wherein no Cladribine is        administered;        wherein the induction period lasts up to about 4 months, or up        to about 3 months, or up to about 2 months; the Cladribine-free        period (ii) lasts up to about 10 months, or up to about 9        months, or up to about 8 months; the maintenance period (iii)        lasts up to about 2 months; the Cladribine-free period (ii)        lasts up to about 10 months; the total effective dose of        Cladribine administered during the maintenance period is about        0.7 mg/kg and steps (iii) to (iv) are performed one, two or        three times.

In another preferred embodiment, the invention provides the use of acombination of Cladribine and IFN-beta for the manufacture of amedicament for treating patients suffering from multiple sclerosis andwho are refractory to at least one conventional therapy for multiplesclerosis, wherein Cladribine is to be orally administered following thesequential steps below:

-   -   (i) An induction period wherein Cladribine is administered and        wherein the total dose of Cladribine reached at the end of the        induction period is from about 1.7 mg/kg to about 3.5 mg/kg;    -   (ii) A Cladribine-free period wherein no Cladribine is        administered;    -   (iii) A maintenance period wherein Cladribine is administered        and wherein the total dose of Cladribine administered during the        maintenance period is lower than the total dose of Cladribine        reached at the end of the induction period (i);    -   (iv) A Cladribine-free period wherein no Cladribine is        administered;        wherein the induction period last up to about 4 months, or up to        about 3 months, or up to about 2 months; the Cladribine-free        period (ii) lasts up to about 10 months, or up to about 9        months, or up to about 8 months; the maintenance period (iii)        lasts up to about 2 months; the Cladribine-free period (iv)        lasts up to about 10 months; the total dose of Cladribine        administered during the maintenance period is about 1.7 mg/kg        and steps (iii) to (iv) are performed one, two or three times.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein Cladribine isto be orally administered at a daily dose of about 3 to 30 mgCladribine, preferably 5 to 20 mg Cladribine, most preferably 10 mgCladribine.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein the total doseof Cladribine reached at the end of the induction period is about 3.5mg/kg and the total dose of Cladribine administered during themaintenance period is about 1.7 mg/kg, preferably 1.75 mg/kg.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein the totaleffective dose of Cladribine reached at the end of the induction periodis about 1.4 mg/kg and the total effective dose of Cladribineadministered during the maintenance period is about 0.7 mg/kg.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein Cladribine isto be orally administered once a day during the induction period.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein Cladribine isto be orally administered several times a day during the inductionperiod, preferably twice or three times a day, more preferably twice aday.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, whereby Cladribine isorally administered about 1 to about 7 days per month, preferably fromabout 4 to about 7 days per month during the induction period, and evenpreferably 4 or 5 days per month during the induction period.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, whereby Cladribine isorally administered about 0.02 days/kg to about 0.08 days/kg per monthduring the induction period.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, whereby Cladribine isorally administered about 0.02 days/kg to about 0.08 days/kg per monthduring the maintenance period.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein Cladribine isto be orally administered at a daily dose of about 10 mg Cladribine fromday 1 to about day 2 each month during the induction period.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein Cladribine isto be orally administered at a daily dose of about 10 mg Cladribine fromday 1 to about day 3 each month during the induction period.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein Cladribine isto be orally administered at a daily dose of about 10 mg Cladribine fromday 1 to about day 4 each month during the induction period.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein Cladribine isto be orally administered at a daily dose of about 10 mg Cladribine fromday 1 to about day 5 each month during the induction period.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein Cladribine isto be orally administered at a daily dose of about 10 mg Cladribine fromday 1 to about day 6 each month during the induction period.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein Cladribine isto be orally administered in a formulation described in WO 2004/087101or in WO 2004/087100. A formulation of Cladribine particularly preferredis the one described in WO 2004/087101, Example 3 or in table 2 ofexample 1 of the present application.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein Cladribine isto be orally administered at a daily dose of about 10 mg Cladribine fromday 1 to about day 4 each month during the induction period and whereinthe pharmaceutical formulation is a pharmaceutical formulation describedin WO 2004/087101 or in WO 2004/087100.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein Cladribine isto be orally administered at a daily dose of about 10 mg Cladribine fromday 1 to about day 5 each month during the induction period and whereinthe pharmaceutical formulation is a pharmaceutical formulation describedin WO 2004/087101 or in WO 2004/087100.

As disclosed here above, Cladribine is administered in combination witha therapeutically effective amount of IFN-beta. The administration oforal Cladribine and IFN-beta may be simultaneous, separate orsequential. Therefore an object of the present invention resides in anyuse of a combination of Cladribine and IFN-beta disclosed herein,wherein Cladribine is to be orally administered following the sequentialsteps disclosed herein and wherein IFN-beta is administeredsimultaneously, separately or sequentially with oral Cladribine.

Another object of the present invention resides in the use of acombination of Cladribine and IFN-beta as disclosed herein, whereinCladribine is to be orally administered following the sequential stepsdisclosed herein and wherein IFN-beta is administered before theinduction period (i), and/or after the maintenance period (iii).

Another object of the present invention resides in the use of acombination of Cladribine and IFN-beta as disclosed herein, whereinCladribine is to be orally administered following the sequential stepsdisclosed herein and wherein IFN-beta is administered during theCladribine-free period (ii) and/or (iv).

In a preferred embodiment of the present invention invention, IFN-betais administered simultaneously with oral Cladribine. Therefore, anotherobject of the present invention resides in the use of a combination ofCladribine and IFN-beta as disclosed herein, wherein Cladribine is to beorally administered following the sequential steps disclosed herein andwherein IFN-beta is administered during the induction period (i) and/orthe maintenance period (iv). Even more preferably, IFN-beta isadministered during the induction period (i), the maintenance period(iv) and the Cladribine-free periods (ii) and (iv). Even morepreferably, IFN-beta is administered before the induction period (i),during the induction period (i), during the maintenance period (iv),during the Cladribine-free periods (ii) and (iv) and after theCladribine-free period (iv).

As disclosed here above, in a preferred embodiment of the presentinvention the IFN-beta protein is chosen in the group consisting of:interferon-beta 1a, such as for example Avonex® (Biogen) or Rebif®(Serono), and interferon-beta 1b, such as for example Betaseron®(Berlex/Schering AG). Preferably, the IFN-beta to be used in the frameof the present invention is Rebif® (Serono).

IFN-beta is preferably administered systemically, and preferablysubcutaneously or intramuscularly. In one embodiment of the presentinvention, the IFN-beta is dosed at least at 44 mcg subcutaneously peradministration. Preferred doses and regimens in accordance with thepresent invention are selected from the group consisting of: 12 MIU (44mcg) of IFN-beta three times a week, 12 MIU (44 mcg) daily, 24 MIU (88mcg) three times a week, 24 MIU (88 mcg) daily. These doses arepreferably administered subcutaneously. In one particularly preferredembodiment, the IFN-beta is dosed at 44 mcg subcutaneously three times aweek, preferably in this case the IFN-beta used is Rebif® (Serono).

Methods of Treatment Using a Combination Therapy of Oral Cladribine andInterferon-Beta (IFN-Beta or IFN-b) According to the Present Invention

In another embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta for treating patients suffering from multiplesclerosis and who are refractory to at least one conventional therapyfor multiple sclerosis, comprising the oral administration of Cladribinefollowing the sequential steps below:

-   -   (i) An induction period wherein Cladribine is administered and        wherein the total dose of Cladribine reached at the end of the        induction period is from about 1.5 mg/kg to about 3.5 mg/kg;    -   (ii) A Cladribine-free period wherein no Cladribine is        administered;    -   (iii) A maintenance period wherein Cladribine is administered        and wherein the total dose of Cladribine administered during the        maintenance period is lower than or equal to the total dose of        Cladribine reached at the end of the induction period (i);    -   (iv) A Cladribine-free period wherein no Cladribine is        administered.

In a preferred embodiment, the invention provides the use of acombination of Cladribine and IFN-beta for treating patients sufferingfrom multiple sclerosis and who are refractory to at least oneconventional therapy for multiple sclerosis, comprising the oraladministration of Cladribine following the sequential steps below:

-   -   (i) An induction period wherein Cladribine is administered and        wherein the total effective dose of Cladribine reached at the        end of the induction period is from about 0.7 mg/kg to about 1.4        mg/kg;    -   (ii) A Cladribine-free period wherein no Cladribine is        administered;    -   (iii) A maintenance period wherein Cladribine is administered        and wherein the total effective dose of Cladribine administered        during the maintenance period is lower than or equal to the        total effective dose of Cladribine reached at the end of the        induction period (i);    -   (iv) A Cladribine-free period wherein no Cladribine is        administered.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein the steps (iii)to (iv) are repeated at least one or two times.

In a preferred embodiment, the invention provides the use of acombination of Cladribine and IFN-beta for treating patients sufferingfrom multiple sclerosis and who are refractory to at least oneconventional therapy for multiple sclerosis, comprising the oraladministration of Cladribine following the sequential steps below:

-   -   (i) Administering Cladribine, such that the total dose of        Cladribine reached at the end of the induction period is from        about 1.7 mg/kg to about 3.5 mg/kg;    -   (ii) Administering no Cladribine during a Cladribine free        period;    -   (iii) Administering Cladribine such that the total dose of        Cladribine administered during a maintenance period is lower        than or equal to the total dose of Cladribine reached at the end        of the induction period (i);    -   (iv) And optionally, a Cladribine-free period wherein no        Cladribine is administered.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein the inductionperiod lasts up to about 4 months, or up to about 3 months, or up toabout 2 months.

In a further preferred embodiment, the invention provides the use of acombination of Cladribine and IFN-beta, as disclosed herein, wherein thetotal dose of Cladribine reached at the end of the induction period isabout 1.7 mg/kg, preferably 1.75 mg/kg. In a preferred embodiment, thetotal dose of Cladribine reached at the end of the induction period isabout 1.7 mg/kg, preferably 1.75 mg/kg, and the induction period lastsup to about 2 months.

In a further preferred embodiment, the invention provides the use of acombination of Cladribine and IFN-beta, as disclosed herein, wherein thetotal dose of Cladribine reached at the end of the induction period isabout 3.5 mg/kg, preferably 3.5 mg/kg. In a preferred embodiment, thetotal dose of Cladribine reached at the end of the induction period isabout 3.5 mg/kg, preferably 3.5 mg/kg, and the induction period lasts upto about 4 months.

In a further preferred embodiment, the invention provides the use of acombination of Cladribine and IFN-beta, as disclosed herein, wherein thetotal effective dose of Cladribine reached at the end of the inductionperiod is about 1.4 mg/kg.

In a further preferred embodiment, the invention provides the use of acombination of Cladribine and IFN-beta, as disclosed herein, wherein theCladribine-free period lasts up to about 10 months, or up to about 9months, or up to about 8 months.

In a further preferred embodiment, the invention provides the use of acombination of Cladribine and IFN-beta, as disclosed herein, wherein themaintenance period lasts up to about 4 months, or up to about 3 monthsor up to about 2 months.

In a further preferred embodiment, the invention provides the use of acombination of Cladribine and IFN-beta, as disclosed herein, wherein thetotal dose of Cladribine administered during the maintenance period isabout 1.7 mg/kg, preferably 1.75 mg/kg.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein the totaleffective dose of Cladribine administered during the maintenance periodis about 0.7 mg/kg.

In a further preferred embodiment, the invention provides the use of acombination of Cladribine and IFN-beta, as disclosed herein, wherein themaintenance period is followed by a Cladribine-free period.

In a further preferred embodiment, the invention provides the use of acombination of Cladribine and IFN-beta, as disclosed herein, wherein thetotal dose of Cladribine reached at the end of the induction period isabout 3.5 mg/kg and the total dose of Cladribine administered during themaintenance period is about 1.7 mg/kg, preferably 1.75 mg/kg.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein the totaleffective dose of Cladribine reached at the end of the induction periodis about 1.4 mg/kg and the total effective dose of Cladribineadministered during the maintenance period is about 0.7 mg/kg.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein Cladribine isto be orally administered at a daily dose of about 3 to about 30 mg.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein Cladribine isto be orally administered at a daily dose of about 10 mg.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein Cladribine isorally administered about 1 to about 7 days per month during theinduction period, preferably from about 4 to about 7 days per monthduring the induction period, and even preferably 4 or 5 days per monthduring the induction period.

In a further embodiment, the invention provides the use of a combinationof Cladribine and IFN-beta, as disclosed herein, wherein the steps (iii)to (iv) are repeated at least one or two times.

As disclosed here above, Cladribine is administered in combination witha therapeutically effective amount of IFN-beta. The administration oforal Cladribine and IFN-beta may be simultaneous, separate orsequential. Therefore an object of the present invention resides in anyuse of a combination of Cladribine and IFN-beta disclosed herein,wherein Cladribine is to be orally administered following the sequentialsteps disclosed herein and wherein IFN-beta is administeredsimultaneously, separately or sequentially with oral Cladribine.

Another object of the present invention resides in the use of acombination of Cladribine and IFN-beta as disclosed herein, whereinCladribine is to be orally administered following the sequential stepsdisclosed herein and wherein IFN-beta is administered before theinduction period (i), and/or after the maintenance period (iii).

Another object of the present invention resides in the use of acombination of Cladribine and IFN-beta as disclosed herein, whereinCladribine is to be orally administered following the sequential stepsdisclosed herein and wherein IFN-beta is administered during theCladribine-free period (ii) and/or (iv).

In a preferred embodiment of the present invention, IFN-beta isadministered simultaneously with oral Cladribine. Therefore, anotherobject of the present invention resides in the use of a combination ofCladribine and IFN-beta as disclosed herein, wherein Cladribine is to beorally administered following the sequential steps disclosed herein andwherein IFN-beta is administered during the induction period (i) and/orthe maintenance period (iv). Even more preferably, IFN-beta isadministered during the induction period (i), the maintenance period(iv) and the Cladribine-free periods (ii) and (iv). Even morepreferably, IFN-beta is administered before the induction period (i),during the induction period (i), during the maintenance period (iv),during the Cladribine-free periods (ii) and (iv) and after theCladribine-free period (iv).

As disclosed here above, in a preferred embodiment of the presentinvention the IFN-beta protein is chosen in the group consisting of:interferon-beta 1a, such as for example Avonex® (Biogen) or Rebif®(Serono), and interferon-beta 1b, such as for example Betaseron®(Berlex/Schering AG). Preferably, the IFN-beta to be used in the frameof the present invention is Rebif® (Serono).

IFN-beta is preferably administered systemically, and preferablysubcutaneously or intramuscularly. In one embodiment of the presentinvention, the IFN-beta is dosed at least at 44 mcg subcutaneously peradministration. Preferred doses and regimens in accordance with thepresent invention are selected from the group consisting of: 12 MIU (44mcg) of IFN-beta three times a week, 12 MIU (44 mcg) daily, 24 MIU (88mcg) three times a week, 24 MIU (88 mcg) daily. These doses arepreferably administered subcutaneously. In one particularly preferredembodiment the IFN-beta is dosed at 44 mcg subcutaneously three times aweek, preferably in this case the IFN-beta used is Rebif® (Serono).

All patent and literature references cited in the present specificationare hereby incorporated by reference in their entirety.

Further aspects and advantages of the present invention will bedisclosed in the following examples, which should be considered asillustrative only, and do not limit the scope of this application.

EXAMPLES

The following abbreviations refer respectively to the definitions below:

kg (kilogram), μg (microgram), mg (milligram), AEs (Adverse effects),CNS (Central nervous system), CSF (Cerebrospinal fluid), EDSS (ExpandedDisability Status Scale, SNRS (Scripps Neurologic Rating Scale), IFN(interferon), i.v. (intra-veinous), MIU (Million International units),MS (multiple sclerosis), MRI (Magnetic resonance imaging), p.o. (peros), PPMS (Primary progressive multiple sclerosis), PRMS (Progressiverelapsing multiple sclerosis), RRMS (Relapsing-remitting multiplesclerosis), SPMS (Secondary progressive multiple sclerosis), s.c.(subcutaneous), TIW (Three times a week), 2-CdA(2-chloro-2′deoxyadenosine or Cladribine), UI (International unit).

The efficacy and safety of oral Cladribine administration, eventuallymulti-dose administration, and of the administration in combination withIFN-beta, according to the invention can be assessed for examplefollowing the protocols below:

Example 1: Oral Cladribine in the Treatment of Relapsing Forms of MS

A study of sixty patients with relapsing forms of clinically definitemultiple sclerosis is undertaken. Each patient is first examined fornormal hepatic, renal, and bone marrow functioning to establish baselinevalues.

Patients are selected from Male or Female, between 18 and 55 years ofage who had one or more relapses within the prior 12 months. Femalepatients are non-pregnant female. Patients are randomly assigned to oneof the treatment groups listed in Table 1 below:

TABLE 1 Group 2-CdA 1 — 2 1.75 mg/kg 3  3.5 mg/kg

Each of the patients in Groups 2 and 3 receives 3 mg or 10 mg 2-CdA (1,2 or 3 administration(s) a day depending on the patient's weight)combined in cyclodextrin formulation as described in WO 2004/087101,Example 3. The Compositions of the Cladribine formulations in 3 mg or 10mg 2-CdA tablets containing hydroxypropyl-beta-cyclodextrin are listedin Table 2 below:

TABLE 2 Formula Formula Name of ingredients mg/tablet mg/tabletCladribine-2- 153.75 30.60 hydroxypropyl-ß- equivalent to equivalent tocyclodextrin-complex* 10 mg 2-CdA 3 mg 2-CdA Sorbitol powder 44.25 68.4Magnesium Stearate 2.0 1.00 (vegetable grade) Total 200.0 100*Cladribine is complexed and lyophilised with2-hydroxypropyl-ß-cyclodextrin as a separate process as described in WO2004/087101.

Examples of administration schemes for the induction period depending onthe patient's weight are given below in Tables 3 and 4 for the targetdoses of 1.75 mg/kg and 3.5 mg/kg respectively. For the maintenanceperiod, the example of administration scheme of Table 3 is applicable.

TABLE 3 Total target dose Patient (kg) Number of pills weight rangesequivalent to (10 mg)/induction (kg) 1.75 mg/kg period Min Mid range MaxMin Max Month 1 Month 2 Total 40 42.5 44.9 28 31.4 4 3 7 45 47.5 49.931.5 34.9 4 4 8 50 52.5 54.9 35 38.4 5 4 9 55 57.5 59.9 38.5 41.9 5 5 1060 62.5 64.9 42 45.4 5 5 10 65 67.5 69.9 45.5 48.9 6 5 11 70 72.5 74.949 52.4 6 6 12 75 77.5 79.9 52.5 55.9 7 6 13 80 82.5 84.9 56 59.4 7 6 1385 87.5 89.9 59.5 62.9 7 7 14 90 92.5 94.9 63 66.4 8 7 15 95 97.5 99.966.5 69.9 8 8 16 100 102.5 104.9 70 73.4 9 8 17 105 107.5 109.9 73.576.9 9 9 18 110 112.5 114.9 77 80.4 9 9 18 115 117.5 119.9 80.5 83.9 109 19

TABLE 4 Total target dose (kg) Patient equivalent weight ranges toNumber of pills (kg) 3.5 mg/kg (10 mg)/induction period Min Mid rangeMax Min Max Month 1 Month 2 Month 3 Month 4 Total 40 42.5 44.9 56 62.9 44 3 3 14 45 47.5 49.9 63 69.9 4 4 4 4 16 50 52.5 54.9 70 76.9 5 4 4 4 1755 57.5 59.9 77 83.9 5 5 5 4 19 60 62.5 64.9 84 90.9 6 5 5 5 21 65 67.569.9 91 97.9 6 6 5 5 22 70 72.5 74.9 98 104.9 6 6 6 6 24 75 77.5 79.9105 111.9 7 7 6 6 26 80 82.5 84.9 112 118.9 7 7 7 6 27 85 87.5 89.9 119125.9 7 7 7 7 28 90 92.5 94.9 126 132.9 8 8 7 7 30 95 97.5 99.9 133139.9 8 8 8 8 32 100 102.5 104.9 140 146.9 9 8 8 8 33 105 107.5 109.9147 153.9 9 9 9 8 35 110 112.5 114.9 154 160.9 10 9 9 9 37 115 117.5119.9 161 167.9 10 10 9 9 38

In Group 1 patients receive a placebo (saline) for 4 months followed by8 months of no treatment.

In Group 2 patients receive a daily oral administration of Cladribinefor about 5 days a month during 2 months (induction period) of 2-CdAcyclodextrin formulation such as the total effective dose administeredat the end of the first 2 months approximates about 0.7 mg/kg (totaldose of about 1.75 mg/kg for a bioavailability of about 40%); followedby administration of placebo for 2 months; followed by 8 months of notreatment.

In Group 3 patients receive a daily oral administration of Cladribinefor about 5 days a month during 4 months (induction period) of 2-CdAcyclodextrin formulation such as the total effective dose administeredat the end of the first 4 months approximates about 1.4 mg/kg (totaldose of about 3.5 mg/kg for a bioavailability of about 40%); followed by8 months of no treatment.

Beginning at month 13, all 3 patient groups receive re-treatment withCladribine cyclodextrin formulation for about 5 days a month for 2months (maintenance period) with the lower dose (such as the totaleffective dose administered at the end of the first 2 monthsapproximates about 0.7 mg/kg) followed by 10 months of no treatment.

Finally, beginning at month 25, all patient groups receive re-treatmentwith Cladribine cyclodextrin formulation for about 5 days a month for 2months (maintenance period) with the lower dose (such as the totaleffective dose administered at the end of the first 2 monthsapproximates about 0.7 mg/kg) followed by 10 more months of notreatment.

Patients are monitored to determine whether there is any progression orimprovement of brain lesions associated with progression of MS throughMRI scans and neurological examination as described in Miller et al.,1996, above; Evans et al., 1997, above; Sipe et al., 1984, above; andMattson, 2002, above. All patients have a baseline and MRI study (brainor spinal cord, according to localization of the lesions) at month 12.

The patient's disability progression and the time for having a firstrelapse are monitored as well as the proportion of relapse-free patientsat 24 months.

Lymphocyte markers and monocyte counts are monitored in the patients.

Patients in Groups 2 and 3 have a decrease in brain lesions.

The data show that the 2-CdA regimen consisting in the succession of aninduction treatment and maintenance treatments is efficient indecreasing brain lesions and no severe adverse effect is observed.

Example 2: Combination Treatment of Oral Cladribine and Rebif® in theTreatment of MS

1. Patients

A study of two hundred and twenty (220) patients with relapsing form ofclinically definite MS and who have experienced at least one relapse inthe preceding 48 weeks prior to screening while taking Rebif® isundertaken.

To qualify for enrollment in this 96-weeks treatment study, subjectshave:

-   -   experienced at least one relapse within the previous 48 weeks        (prior to Screening) and;    -   been receiving Rebif® for at least 48 weeks prior to Screening.

Patients are selected from male or female, 18-55 years of age(inclusive), weight between 40-120 kg, inclusive.

Once enrolled, these subjects experiencing active MS symptoms whiletaking Rebif® are randomized in a 2:2:1 ratio to receive high dosecladribine (N=89, defined as Group 3, see table 1), low dose cladribine(N=89; defined as Group 2, see table 1) or placebo (N=42; defined asGroup 1, see table 1) add-on to their existing Rebif® regimen.

For this study, subjects receiving placebo as add-on therapy to theirexisting Rebif® regimen are the control group. Subjects' responses toadd-on cladribine to Rebif® therapy, with respect to safety,tolerability, and efficacy, are compared to subjects' responses toplacebo add-on to Rebif® therapy.

2. Products

Subjects entering the study are provided with Cladribine presented in 10mg tablets in a complex with 2-hydroxypropyl-β-cyclodextrin (see Table2), and Rebif®.

Rebif® is supplied as a sterile solution in ready-to-use pre-filledsyringe at 44 mcg (0.5 mL volume), intended for subcutaneousadministration.

The dosage of Rebif® is 44 mcg injected subcutaneously three times perweek.

Cladribine is presented in tablets containing 10 mg of cladribine in acomplex with 2-hydroxypropyl-β-cyclodextrin (see Table 2).

The matching placebo tablets have the same composition as the cladribinetablets but do not contain cladribine. For placebo, cladribine isreplaced by 10 mg of 2-hydroxypropyl-β-cyclodextrin.

3. Administration Scheme

Dose: Cladribine is administered orally in 10 mg tablets. The number oftablets to be administered is standardized based on weight, using 10 kgweight ranges (i.e. 60-69.9 kg, 70-79.9 kg, etc.; see table 7),dispensed in blister packs ranging from four to ten tablets, dependingon the weight range and treatment arm to which a subject is randomized.

The total number of tablets dispensed in a blister pack should beadministered evenly over a 4-5 day period. For example, a subject whoreceives five tablets should take one a day for five days; whereas asubject who receives seven tablets should take two on Day 1, two on Day2, one on Day 3, one on Day 4 and one on Day 5 (see table 5).

Table 5 illustrates the breakdown of daily tablet administration for onecycle of treatment.

TABLE 5 Daily Cladribine tablet Administration for one cycle oftreatment Total # of Day of Cycle Tablets Dispensed Day 1 Day 2 Day 3Day 4 Day 5 4 1 1 1 1 0 5 1 1 1 1 1 6 2 1 1 1 1 7 2 2 1 1 1 8 2 2 2 1 19 2 2 2 2 1 10 2 2 2 2 2

Patients who receive Cladribine receive it during two periods. The firstperiod is named the induction period and the second period is named themaintenance period.

TABLE 6 Type of Cladribine Tablets Per CYCLE and By Treatment Arm TotalYearly Cumulative cumulative Yearly Dose dose cumulative (InductionCycle 1 Cycle 2 Cycle 3 Cycle 4 (Induction Cycle 5 Cycle 6 dose and ArmDay 1 Wk5 Wk9 Wk13 Treatment) Wk48 Wk52 (maintenance) Maintenance)Placebo Placebo Placebo Placebo Placebo   0 mg/kg Placebo Placebo   0mg/kg   0 mg/kg Low Active Active Placebo Placebo 1.75 mg/kg ActiveActive 1.75 mg/kg  3.5 mg/kg Dose High Active Active Active Active  3.5mg/kg Active Active 1.75 mg/kg 5.25 mg/kg Dose

Induction Period (Weeks 5, 9, 13)

The first 48 weeks correspond to the induction period (start of StudyDay 1 through end of Week 47). The three groups of patients follow thefollowing scheme (see table 6):

Group 3 (High-dose Cladribine) receive 0.875 mg/kg/cycle for fourconsecutive cycles;

Group 2 (Low-dose Cladribine) receive 0.875 mg/kg/cycle for twoconsecutive cycles+placebo for two cycles;

Group 1 (Placebo) receive placebo for four consecutive cycles.

Following the initial course of treatment dispensed at Study Day 1, eachsubject return for three additional treatments, at four-week intervals,at the start of Weeks 5, 9, and 13 (see table 6).

Since accurate drug dosing of cladribine/placebo is based on weight,prior to dispensing cladribine/placebo tablets at the start of Weeks 5,9 and 13, the subject's weight should be accurately assessed.

All the patients receive low-dose or high-dose cladribine tablets orplacebo as an “add-on” to their ongoing Rebif® treatment regimen duringthe induction period.

Maintenance Period (Weeks 48 and 52)

In the maintenance period (Weeks 48 through 96), subjects who receivedcladribine in the induction period then receive low-dose cladribine(0.875 mg/kg/cycle for two cycles, see table 6), added to Rebif®, whilethose who received placebo continue to receive placebo (for two cyclessee table 6), added to Rebif®.

The tablets of Cladribine are 10 mg in strength and are dispensed, basedon standardized 10 kg weight ranges (see table 7). Each treatment cycleare defined as individual daily oral doses of cladribine tabletsadministered for 4-5 consecutive days (see table 5) during a 28-dayperiod.

TABLE 7 Number of Cladribine Tablets Per cycle And Per Weight Group HighDose (0.875 mg/kg/ cycle for 4 cycles) Number of Number of Tablets/CycleTablets/Cycle Weight Ranges (Treatment) (Retreatment) Mid Cycle ActivePlacebo Total Cycle Active Placebo Total Min Range Max 1 Cycle 2 Cycle 3Cycle 4 Tablets Tablets Tablets 1 Cycle 2 Tablets Tablets Tablets 40 4549.9 4 4 4 4 16 16 4 4 8 8 50 55 59.9 5 5 5 5 20 20 5 5 10 10 60 65 69.96 6 6 5 23 23 6 6 12 12 70 75 79.9 7 7 7 6 27 27 7 7 14 14 80 85 89.9 87 8 7 30 30 8 7 15 15 90 95 99.9 9 8 9 8 34 34 9 8 17 17 100 105 109.910 9 9 9 37 37 10 9 19 19 110 115 119.9 10 10 10 10 40 40 10 10 20 20Low Dose (0.875 mg/kg/ cycle for 2 cycles + placebo for 2 cycles) Numberof Number of Tablets/Cycle Tablets/Cycle Weight Ranges (Treatment)(Retreatment) Mid Cycle Active Placebo Total Cycle Active Placebo TotalMin Range Max 1 Cycle 2 Cycle 3 Cycle 4 Tablets Tablets* Tablets 1 Cycle2 Tablets Tablets Tablets 40 45 49.9 4 4

8

16 4 4 8 8 50 55 59.9 5 5

10

20 5 5 10 10 60 65 69.9 6 6

12

23 6 6 12 12 70 75 79.9 7 7

14

27 7 7 14 14 80 85 89.9 8 7

15

30 8 7 15 15 90 95 99.9 9 8

17

34 9 8 17 17 100 105 109.9 10 9

19

37 10 9 19 19 110 115 119.9 10 10

20

40 10 10 20 20 Placebo (4 cycles) Number of Number of Tablets/CycleTablets/Cycle Weight Ranges (Treatment) (Retreatment) Mid Cycle ActivePlacebo Total Cycle Active Placebo Total Min Range Max 1 Cycle 2 Cycle 3Cycle 4 Tablets Tablets* Tablets 1 Cycle 2 Tablets Tablets* Tablets 4045 49.9

16

8 50 55 59.9

20

10 60 65 69.9

23

12 70 75 79.9

27

14 80 85 89.9

30

15 90 95 99.9

34

17 100 105 109.9

37

19 110 115 119.9

40

20 *Placebo tablets are in bold italic underlined.

The study is designed to evaluate the safety, tolerability and efficacyof oral Cladribine when added to Rebif® in multiple sclerosis subjectswith active disease compared to placebo when added to Rebif® in the samepopulation of subjects.

In particular, the sample size for this study is designed to detect areduction in the mean number of T₁ gadolinium-enhanced lesions persubject after 96 weeks of Rebif® plus Cladribine compared to Rebif® plusplacebo add-on therapy in subjects who had at least one relapse whiletaking Rebif® in the 48 weeks prior to entering this study.

Lymphocyte markers and monocyte counts are monitored in the patients.

Patients are monitored to determine whether there is any progression orimprovement of brain lesions associated with progression of MS throughMRI scans and neurological examination as described in Miller et al.,1996, above; Evans et al., 1997, above; Sipe et al., 1984, above; andMattson, 2002, above.

The patient's disability progression and the time for having a firstrelapse are monitored as well as the proportion of relapse-free patientsat 24 months.

The efficacy of the treatment is measured by the frequency of relapsesin RRMS and the monitoring of the lesions in the CNS as detected usingmethods such as MRI technique (Miller et al., 1996, Neurology, 47(Suppl4): S217; Evans et al., 1997, Ann. Neurology, 41:125-132).

The observation of the reduction and/or suppression of MRI T₁gadolinium-enhanced lesions (thought to represent areas of activeinflammation) gives a primary efficacy variable.

Secondary efficacy variables include number of combined active lesionsper subject defined as new T1 gadolinium-enhancing, or new T2non-enhancing, or enlarging lesions, or both (without double-counting);number of active T2 lesions per subject; number of active T1gadolinium-enhanced lesions per subject; proportion of subjects with noactive T2 lesions; proportion of subjects with no active T1gadolinium-enhanced lesions; change in T2 lesion volume; relapse rate;Expanded Disability Status Scale score and Scripps Neurologic RatingScale (SNRS) score (Sipe et al., 1984, Neurology, 34, 1368-1372).

Patients in Groups 2 and 3 have a decrease in brain lesions.

The data show that the 2-CdA regimen consisting in the succession of aninduction treatment and maintenance treatments combined with a treatmentwith Rebif® is efficient in decreasing brain lesions of and no severeadverse effect is observed.

A follow-up extension study for an additional 48 weeks duration at theconclusion of this 96-week trial is possible. The follow-up extensionstudy dosing starts with the Week 96. Subjects receive Cladribine 1.75mg/kg/year provided over 2 cycles+Rebif® 44 mcg TIW following the samescheme as the maintenance period described here above.

We claim:
 1. A method of treating patients suffering from multiplesclerosis and who are refractory to at least one conventional therapyfor multiple sclerosis comprising administering IFN-β in combinationwith cladribine, wherein cladribine is orally administered following thesequential steps below: (i) An induction period wherein cladribine isadministered and wherein the total dose of cladribine reached at the endof the induction period is from about 1.7 mg/kg to about 3.5 mg/kg; (ii)A cladribine-free period wherein no cladribine is administered; (iii) Amaintenance period wherein cladribine is administered and wherein thetotal dose of cladribine administered during the maintenance period islower than or equal to the total dose of cladribine reached at the endof the induction period (i); and (iv) A cladribine-free period whereinno cladribine is administered.
 2. The method of claim 1, wherein thecombined duration of the induction period (i) with the cladribine-freeperiod (ii) is about 1 year.
 3. The method of claim 2, wherein theduration of the induction period is about 4 months and the duration ofthe cladribine-free period (ii) is about 8 months, or the duration ofthe induction period is about 2 months and the duration of thecladribine-free period (ii) is about 10 months.
 4. The method of claim2, wherein the combined duration of the induction period (i) with thecladribine-free period (ii) is about 1 year (about 12 months) and thetotal dose of cladribine reached at the end of this year of treatment isabout 1.7 mg/kg or about 3.5 mg/kg.
 5. The method of claim 1, whereinthe combined duration of the maintenance period (iii) with thecladribine-free period (iv) is about 1 year.
 6. The method of claim 5,wherein the duration of the maintenance period (iii) is about 2 monthsand the duration of the cladribine-free period (iv) is about 10 months.7. The method of claim 5, wherein the combined duration of themaintenance period (iii) with the cladribine-free period (iv) is about 1year and the total dose of cladribine administered during this year oftreatment is about 1.7 mg/kg.
 8. The method of claim 1, wherein thecombined duration of the induction period (i), the cladribine-freeperiod (ii), the maintenance period (iii) and the cladribine-free period(iv) is about 2 years.
 9. The method of claim 8, wherein: the durationof the induction period is about 4 months, the duration of thecladribine-free period (ii) is about 8 months, the duration of themaintenance period (iii) is about 2 months and the duration of thecladribine-free period (iv) is about 10 months; or; the duration of theinduction period is about 2 months, the duration of the cladribine-freeperiod (ii) is about 10 months, the duration of the maintenance period(iii) is about 2 months and the duration of the cladribine-free period(iv) is about 10 months.
 10. The method of claim 8, wherein the combinedduration of the induction period (i) and the cladribine-free period (ii)is about 1 year, the combined duration of the maintenance period (iii)and the cladribine-free period (iv) is about 1 year, the total dose ofCladribine administered during the first year of treatment is about 1.7mg/kg and the total dose of cladribine administered during the secondyear of treatment is about 1.7 mg/kg.
 11. The method of claim 10,wherein the total dose of cladribine administered during the first yearof treatment is about 1.75 mg/kg.
 12. The method of claim 8, wherein thecombined duration of the induction period (i) and the cladribine-freeperiod (ii) is about 1 year, the combined duration of the maintenanceperiod (iii) and the cladribine-free period (iv) is about 1 year, thetotal dose of cladribine administered during the first year of treatmentis about 3.5 mg/kg and the total dose of cladribine administered duringthe second year of treatment is about 1.7 mg/kg.
 13. The method of claim1, wherein steps (iii) to (iv) are repeated one, two or three times. 14.The method of claim 1, wherein the total effective dose of cladribinereached at the end of the induction period is about 0.7 mg/kg or about1.4 mg/kg.
 15. The method of claim 1, wherein the total effective doseof cladribine administered during the maintenance period is about 0.7mg/kg.
 16. The method of claim 1, wherein cladribine is administeredfrom 4 to 7 days per month during the induction period.
 17. The methodof claim 16, wherein cladribine is administered at a daily dose of about0.175 mg/kg during the induction period.
 18. The method of claim 1,wherein cladribine is administered from day 1 to day 5 each month duringthe induction period.